Tiny SC/MP system !!! - UK Vintage Radio Repair and Restoration Discussion Forum

Phil__G · 26th Aug 2023, 9:22 pm

I was looking at the memory expansion PCB that I'd used on the latest MK14v6, and started pondering... it has a scamp, rom, ram, a gal address decoder... its pretty much a complete computer so I thought maybe you could run Kitbug on it, with 1k rom and 3k ram, have the gal invert the flag 0 serial output... the tinyest kitbug machine!

Well, I tried it and yes its now running Kitbug standalone! Its actually the eprom image I did for the Aitken machine, so there are a few features beyond the original NS Kitbug - and (for now) it has the famous bit7 serial bug which I'd forgotten about. The crystal is under the sc/mp and theres a reset cap etc added.
Presently trying to port KitbugPlus but I used a lot of PICL specific code in there and I cant remember what I did... also Karen reduced GECO and PUTC to single byte pseudo-ops, when i expand these back to sc/mp code the monitor is 60 odd bytes larger and wont fit in the 1k... the gal presently splits it 1k rom 3k ram so I'll have to expand the rom area to get kb+ in there...
Just a bit of timewasting fun rather than doing my chores...

Cheers
Phil

Mark1960 · 27th Aug 2023, 12:52 am

Not sure what you connected to the gal but it could probably also latch the upper bytes of the address and run NIBL.

I was thinking earlier that your MK14 was only being used as a keyboard and display.

Phil__G · 27th Aug 2023, 10:40 am

I think you could Mark but I've only ever done simple gal equations. There are plenty of wincupl examples but I havent found much using just eqn2jed, I need to buck up and learn wincupl

A wierd problem delayed the project for an evening - with /hold, cont & /busrq all needing to be held high I commoned them together and used a single 1k pull-up. It didnt run and I found the commoned inputs tested low, even with the pull-up. As with many simple sc/mp designs I changed /nbreq to its own pullup and wired cont and /hold to vcc, and it sprang into life. I couldnt find anything in the datasheet that would explain this (?) unless one of them does something during startup, maybe bus arbitration or something. Or if cont or /hold pull a lot of current. It was only an experiment for fun, but its encouraged me towards a 'proper' sc/mp board

Cheers - Phil

Timbucus · 27th Aug 2023, 12:16 pm

Cracking idea Phil...

TonyDuell · 27th Aug 2023, 1:29 pm

NBREQ is a bidirectional pin. It might well pull low momentarily after reset, and if that then asserts NHOLD and deasserts CONT it is quite likely the thing will not run.

Mark1960 · 27th Aug 2023, 3:27 pm

As Tony said, NBREQ is both an input and an output. It is pulled low by the 8060 at the start of every bus access. I think once the bus access is started CONT will be ignored, but NHOLD will make it wait at the end of the bus cycle and never finish.

Michael Haardt · 27th Aug 2023, 4:34 pm

I would welcome your spiced up version of Kitbug for native hardware. The bit 7 fix is simple: Add this in GECO towards the end:

CAS
DLD -1(P2) ; DECREMENT BIT COUNT
JNZ $LOOP ; LOOP UNTIL 0
+ LDI 045 ; DELAY BIT TIME FOR MSB
+ DLY 1
CSA ; SET STOP BIT
ANI 0FE

Phil__G · 27th Aug 2023, 5:54 pm

Thanks Michael, the KitbugPlus monitor I did for the PICL was in SC/MP assembler but used Karens PIC pseudo-ops for GECO, PUTC and break, and I'm finding its not as straightforward as I expected to convert these back to straight SC/MP code. Simply expanding the pseudo-ops to SC/MP source has introduced quite a few problems which I'm still working through.
The intention is to have a comprehensive monitor for native SC/MP systems (the original NS Kitbug was very limited - type, modify and go!).
KitbugPlus has everything integrated properly but the version on the Aitken machine ( https://www.youtube.com/watch?v=1WU7DbC8Sac ) is pretty much the original NS Kitbug with a nicer prompt and a hex-dump (hex only, no ascii, KB+ does both), inline print and formatted list added, but these routines are separate programs in the rom and not integrated into Kitbug - just tagged onto the end of the rom. They're executed by setting registers at FF7--> and 'Go' like any other program:

Code:

01FC-                399        ;       MEMORY DUMP COMMAND
0200                400                .NO     $200    ; TO MATCH EXISTING ROM
0200-                401        ;
0200-C4 F6           402 (  10) DUMP:   LDI     $0F6
0202-32              403 (   8)         XPAL    P2
0203-C4 0F           404 (  10)         LDI     $0F
0205-36              405 (   8)         XPAH    P2
0206-C4 10           406 (  10) DLOOP1: LDI     16              ; 16 bytes/line
0208-CA F8           407 (  18)         ST      -8(P2)
020A-C4 02           408 (  10)         LDI     /IPRINT         ; ALL EXTENSION
020C-37              409 (   8)         XPAH    P3
020D-C4 2F           410 (  10)         LDI     #IPRINT-1
020F-33              411 (   8)         XPAL    P3
0210-3F              412 (   7)         XPPC    P3              ; PRINT CRLF
0211-0D 0A 00        413                .DB     $0D,$0A,0
0214-35              414 (   8)         XPAH    P1              ; GET HIGH ADDR
0215-01              415 (   7)         XAE
0216-40              416 (   6)         LDE
0217-35              417 (   8)         XPAH    P1
0218-C4 01           418 (  10)         LDI     /PHEX2
021A-37              419 (   8)         XPAH    P3
021B-C4 43           420 (  10)         LDI     #PHEX2-1
021D-33              421 (   8)         XPAL    P3
021E-3F              422 (   7)         XPPC    P3              ; PRINT HEX BYTE & SPACE
021F-40              423 (   6)         LDE
0220-3F              424 (   7)         XPPC    P3
0221-31              425 (   8)         XPAL    P1              ; GET LOW ADDR
0222-01              426 (   7)         XAE
0223-40              427 (   6)         LDE
0224-31              428 (   8)         XPAL    P1
0225-40              429 (   6)         LDE
0226-3F              430 (   7)         XPPC    P3
0227-C5 01           431 (  18) DLOOP2: LD      @+1(P1)
0229-3F              432 (   7)         XPPC    P3              ; PRINT HEX BYTE & SPACE
022A-BA F8           433 (  22)         DLD     -8(P2)
022C-9C F9           434 (9/11)         JNZ     DLOOP2
022E-90 D6           435 (  11)         JMP     DLOOP1
0230-                436        ;
0230-                437        ;       INLINE PRINT - TEXT FOLLOWS XPPC P3 CALL, ZERO TERMINATED
0230-                438        ;
0230-33              439 (   8) IPRINT: XPAL    P3
0231-31              440 (   8)         XPAL    P1
0232-37              441 (   8)         XPAH    P3
0233-35              442 (   8)         XPAH    P1
0234-C4 C4           443 (  10)         LDI     #PUTC-1
0236-33              444 (   8)         XPAL    P3
0237-C4 01           445 (  10)         LDI     /PUTC
0239-37              446 (   8)         XPAH    P3
023A-C5 01           447 (  18) IGET:   LD      @+1(P1)
023C-98 05           448 (9/11)         JZ      IDONE
023E-3F              449 (   7)         XPPC    P3
023F-90 F9           450 (  11)         JMP     IGET
0241-C5 FF           451 (  18)         LD      @-1(P1)
0243-31              452 (   8) IDONE:  XPAL    P1
0244-33              453 (   8)         XPAL    P3
0245-35              454 (   8)         XPAH    P1
0246-37              455 (   8)         XPAH    P3
0247-3F              456 (   7)         XPPC    P3
0248-90 E6           457 (  11)         JMP     IPRINT
024A-                458        ;
0250                459                .NO     $250    ; TO MATCH EXISTING ROM
0250-                460        ;       Formatted list, instruction-length-aware
0250-C4 F6           461 (  10) FLIST:  LDI     #P2ADR
0252-32              462 (   8)         XPAL    P2
0253-C4 0F           463 (  10)         LDI     /P2ADR
0255-36              464 (   8)         XPAH    P2
0256-C4 C4           465 (  10) FL2:    LDI     #PUTC-1         ; PRINT CR-LF
0258-33              466 (   8)         XPAL    P3
0259-C4 01           467 (  10)         LDI     /PUTC
025B-37              468 (   8)         XPAH    P3
025C-C4 0D           469 (  10)         LDI     $0D
025E-3F              470 (   7)         XPPC    P3              ; PRINT CR
025F-C4 0A           471 (  10)         LDI     $0A
0261-3F              472 (   7)         XPPC    P3              ; PRINT LF
0262-35              473 (   8)         XPAH    P1              ; PRINT HIGH BYTE
0263-01              474 (   7)         XAE                     ; READ AND RESTORE BYTE FROM P1
0264-40              475 (   6)         LDE
0265-35              476 (   8)         XPAH    P1
0266-C4 43           477 (  10)         LDI     #PHEX2-1
0268-33              478 (   8)         XPAL    P3
0269-40              479 (   6)         LDE
026A-3F              480 (   7)         XPPC    P3              ; CALL PHEX2
026B-31              481 (   8)         XPAL    P1              ; PRINT LOW BYTE
026C-01              482 (   7)         XAE
026D-40              483 (   6)         LDE
026E-31              484 (   8)         XPAL    P1
026F-40              485 (   6)         LDE
0270-3F              486 (   7)         XPPC    P3
0271-C5 01           487 (  18)         LD      @+1(P1)
0273-3F              488 (   7)         XPPC    P3
0274-C1 FF           489 (  18)         LD      -1(P1)
0276-94 DE           490 (9/11)         JP      FL2
0278-C5 01           491 (  18)         LD      @+1(P1)
027A-3F              492 (   7)         XPPC    P3
027B-90 D9           493 (  11)         JMP     FL2
027D-                494        ;

Mark1960 · 27th Aug 2023, 7:14 pm

It would be nice if you could make it compatible with the single step circuit of the revised MK14 monitor and include coolsnaz fast loader.

Phil__G · 27th Aug 2023, 9:05 pm

Replicating the single-step circuitry in the gal is beyond me Mark

I'd intended a hex loader but theres plenty of room for the fast-loader too
Might not be soon though

Cheers
Phil

Mark1960 · 28th Aug 2023, 1:38 am

I was only thinking it would be nice to have the software support for the single step in your version of the monitor, I hadn’t considered trying to put that in the gal. I use that part of the MK14 monitor to release then next processor on the multiprocessor.

I guess the fast loader might not make much sense either, you have a terminal emulator connected so you can just send a file direct from the terminal if it can load hex files.

Phil__G · 29th Aug 2023, 12:55 pm

After a lot of headscratching I found a self-inflicted problem with the inline print, in recreating 40-year old scribbles I had misplaced a label. In the code in post #8 the label "IDONE:" should be one-line up, by the "LD @-1(P1)" - the symptom was that the return address wasnt decremented as it should have been.
This is why I dont like posting code on the forum as we cant correct mistakes, but heres the corrected code, sorry for the whoopsie.
This SBASM source has been recreated from hand-written code from 40+ years ago and still working in the Andrew Aitken machine.
It also works perfectly in the "MK14 Memory expansion PCB" as a stand-alone "micro-introkit"

(with more memory than the original, 1k rom 3k ram)

Code:

0000-                  4        ;
0000-                  5        ; Phils Kitbug extensions from 1980, load from 0x200 after Kitbug
0000-                  6        ; Assumes 'GECO fixed' Kitbug with PUTC at 01C9
0000-                  7        ; Optionally change to a nice prompt by editing 0x040 to 0x4E
0000-                  8        ; FROM: C4 01 37 C4 C8 33 C4 0D 3F C4 0A 3F C4 2D 3F
0000-                  9        ; TO:   C4 02 37 C4 7F 33 3F 08 08 08 08 08 08 08 08
0000-                 10        ; Utils: set 0xFF9 to required memory start highbyte,
0000-                 11        ;        set 0xFFA to required memory start lowbyte
0000-                 12        ; DUMP - set 0xFF7 to 02, 0xFF8 to 00, then Go
0000-                 13        ; LIST - set 0xFF7 to 02, 0xFF8 to 30, then Go
0000-                 14        ; ILPRINT - point P3 to ILPRINT-1, use inline text, 0 term
0000-                 15        ;        see PROMPT: below for an example
0000-                 16        ;
0186-                 17        GECO    .EQ     0X0186
01C9-                 18        PUTC    .EQ     0X01C9  ; NOTE OFFSET FROM ORIGINAL BY GECO FIX
0144-                 19        PHEX2   .EQ     0X0144
004F-                 20        CMDLP2  .EQ     0X004F
0FF6-                 21        P2ADR   .EQ     0X0FF6
0000-                 22
0000-                 23        ; Memory dump at $0200 and instr-length-aware list at $0250
0000-                 24        ; Inline print at $0230 and prompt extension at $0280.  Phil_G.
0000-                 25        ;
0001-                 26        P1      =       1
0002-                 27        P2      =       2
0003-                 28        P3      =       3
0000-                 29        ;
0000-                 30        ;       MEMORY DUMP COMMAND
0200-                 31                .OR     $200    ; IMMEDIATELY AFTER KITBUG (512 BYTES)
0200-                 32        ;
0200-C4 F6            33 (  10) DUMP:   LDI     #P2ADR
0202-32               34 (   8)         XPAL    P2
0203-C4 0F            35 (  10)         LDI     /P2ADR
0205-36               36 (   8)         XPAH    P2
0206-C4 10            37 (  10) DLOOP1: LDI     16              ; 16 bytes/line
0208-CA F8            38 (  18)         ST      -8(P2)
020A-C4 01            39 (  10)         LDI     /PUTC           ; ALL EXTENSION
020C-37               40 (   8)         XPAH    P3
020D-C4 C8            41 (  10)         LDI     #PUTC-1
020F-33               42 (   8)         XPAL    P3
0210-C4 0D            43 (  10)         LDI     $0D
0212-3F               44 (   7)         XPPC    P3              ; PRINT CR
0213-C4 0A            45 (  10)         LDI     $0A
0215-3F               46 (   7)         XPPC    P3              ; PRINT LF
0216-                 47
0216-35               48 (   8)         XPAH    P1              ; GET HIGH ADDR
0217-01               49 (   7)         XAE
0218-40               50 (   6)         LDE
0219-35               51 (   8)         XPAH    P1
021A-                 52        ;       LDI     /PHEX2
021A-                 53        ;       XPAH    P3
021A-C4 43            54 (  10)         LDI     #PHEX2-1
021C-33               55 (   8)         XPAL    P3
021D-40               56 (   6)         LDE                     ; *** WAS MISSING ***
021E-3F               57 (   7)         XPPC    P3              ; PRINT HEX BYTE & SPACE
021F-31               58 (   8)         XPAL    P1              ; GET LOW ADDR
0220-01               59 (   7)         XAE
0221-40               60 (   6)         LDE
0222-31               61 (   8)         XPAL    P1
0223-40               62 (   6)         LDE
0224-3F               63 (   7)         XPPC    P3
0225-C5 01            64 (  18) DLOOP2: LD      @+1(P1)
0227-3F               65 (   7)         XPPC    P3              ; PRINT HEX BYTE & SPACE
0228-BA F8            66 (  22)         DLD     -8(P2)
022A-9C F9            67 (9/11)         JNZ     DLOOP2
022C-90 D8            68 (  11)         JMP     DLOOP1
022E-                 69        ;
0230                 70                .NO     0X230
0230-                 71        ;
0230-                 72        ;       INLINE PRINT - TEXT FOLLOWS XPPC P3 CALL, ZERO TERMINATED
0230-                 73        ;
0230-33               74 (   8) IPRINT: XPAL    P3
0231-31               75 (   8)         XPAL    P1
0232-37               76 (   8)         XPAH    P3
0233-35               77 (   8)         XPAH    P1
0234-C4 C8            78 (  10)         LDI     #PUTC-1
0236-33               79 (   8)         XPAL    P3
0237-C4 01            80 (  10)         LDI     /PUTC
0239-37               81 (   8)         XPAH    P3
023A-C5 01            82 (  18) IGET:   LD      @+1(P1)
023C-98 03            83 (9/11)         JZ      IDONE
023E-3F               84 (   7)         XPPC    P3
023F-90 F9            85 (  11)         JMP     IGET
0241-C5 FF            86 (  18) IDONE:  LD      @-1(P1) ; ADJUST RETURN ADDRESS
0243-31               87 (   8)         XPAL    P1
0244-33               88 (   8)         XPAL    P3
0245-35               89 (   8)         XPAH    P1
0246-37               90 (   8)         XPAH    P3
0247-3F               91 (   7)         XPPC    P3
0248-90 E6            92 (  11)         JMP     IPRINT
024A-                 93        ;
0250                 94                .NO     $250    ; TO MATCH EXISTING ROM
0250-                 95        ;       Formatted list, instruction-length-aware
0250-C4 F6            96 (  10) FLIST:  LDI     #P2ADR
0252-32               97 (   8)         XPAL    P2
0253-C4 0F            98 (  10)         LDI     /P2ADR
0255-36               99 (   8)         XPAH    P2
0256-C4 C8           100 (  10) FL2:    LDI     #PUTC-1         ; PRINT CR-LF
0258-33              101 (   8)         XPAL    P3
0259-C4 01           102 (  10)         LDI     /PUTC
025B-37              103 (   8)         XPAH    P3
025C-C4 0D           104 (  10)         LDI     $0D
025E-3F              105 (   7)         XPPC    P3              ; PRINT CR
025F-C4 0A           106 (  10)         LDI     $0A
0261-3F              107 (   7)         XPPC    P3              ; PRINT LF
0262-35              108 (   8)         XPAH    P1              ; PRINT HIGH BYTE
0263-01              109 (   7)         XAE                     ; READ AND RESTORE BYTE FROM P1
0264-40              110 (   6)         LDE
0265-35              111 (   8)         XPAH    P1
0266-C4 43           112 (  10)         LDI     #PHEX2-1
0268-33              113 (   8)         XPAL    P3
0269-40              114 (   6)         LDE
026A-3F              115 (   7)         XPPC    P3              ; CALL PHEX2
026B-31              116 (   8)         XPAL    P1              ; PRINT LOW BYTE
026C-01              117 (   7)         XAE
026D-40              118 (   6)         LDE
026E-31              119 (   8)         XPAL    P1
026F-40              120 (   6)         LDE
0270-3F              121 (   7)         XPPC    P3
0271-C5 01           122 (  18)         LD      @+1(P1)
0273-3F              123 (   7)         XPPC    P3
0274-C1 FF           124 (  18)         LD      -1(P1)
0276-94 DE           125 (9/11)         JP      FL2
0278-C5 01           126 (  18)         LD      @+1(P1)
027A-3F              127 (   7)         XPPC    P3
027B-90 D9           128 (  11)         JMP     FL2
027D-                129        ;
0280                130                .NO     $280    ; TO MATCH EXISTING ROM;        SIGN-ON EXTENSION
0280-                131        ;
0280-C4 2F           132 (  10) PROMPT: LDI     #IPRINT-1
0282-33              133 (   8)         XPAL    P3
0283-C4 02           134 (  10)         LDI     /IPRINT
0285-37              135 (   8)         XPAH    P3
0286-3F              136 (   7)         XPPC    P3
0287-0D 0A 4B 69 
     74 62 75 67 
     0D 0A 3E 00     137                .DB     $0D,$0A,"Kitbug",$0D,$0A,">",0
0293-C4 4E           138 (  10)         LDI     #CMDLP2-1
0295-33              139 (   8)         XPAL    P3
0296-C4 00           140 (  10)         LDI     /CMDLP2
0298-37              141 (   8)         XPAH    P3
0299-3F              142 (   7)         XPPC    P3
029A-                143        ;
029A-                144                .END

If anyone fancies a go, eeprom and gal files attached.

Phil__G · 30th Aug 2023, 1:07 am

Update, I have KitbugPlus running on the little SC/MP board, actually its proving to be a brilliant development test-bed

I changed the gal to give 2k rom 2k ram, or could do 1.5k rom 2.5k ram, need to allow room for a couple of routines, Block move, Intel hexloader, etc
But as it stands its running great, much more practical than the original Kitbug!
Source is at the bottom of the sc/mp page, its a working copy but likely to be updated as & when...
Cheers
Phil

audiokit · 30th Aug 2023, 10:12 am

Hello Phil.
Wow, that was a quick one after all! congrats and I will see if I can try it out soon. Indeed much better then the original kitbug which is very limited in its use.

Phil__G · 30th Aug 2023, 4:06 pm

Thanks Benny, I'd be interested to hear how you find it, presently it needs one-and-a-quarter kilobytes but if you allow 2k then we'll have room for updates such as the hex-loader which has to be the next priority

I'm really enjoying the novelty of this tiny board, about 60mm square, and being able to change the address decoding at will is great for experimenting

(within the 4k page of course)

Phil__G · 31st Aug 2023, 11:23 pm

Just a demo, Music (from the SoC manual) for Kitbug or KitbugPlus on the tiny board.
The file music.dat is the keying file, in Teraterm type M800 (ret) and then from the menubar, File, send-file music.dat
When its finished loading, enter G800 to run

Phil__G · 1st Sep 2023, 10:11 pm

I did a brief document for the project, http://philg.uk, bottom of the SC/MP page
If anyone facies a go I have a few pcbs and can do a programmed GAL at cost, no profit
Cheers
Phil

Realtime · 2nd Sep 2023, 1:04 pm

Nice description of the project - very easy to follow. Might benefit from including a memory map. I expect that info is easily available else where but keeps it all together. I'll p.m you regarding a PCB and GAL in due course - another project to add to the ever growing list

Phil__G · 2nd Sep 2023, 6:25 pm

Thanks Ian - updated a few minutes ago.

Phil__G · 2nd Sep 2023, 10:48 pm

KitbugPlus now has a Serial loader, using the command Sxxx where xxx is the load address, and then sending a bin file using Teraterm (tick the bin option on the file, send screen)
Its a binary loader cos in working on Intel Hex I was having to use silly long delays whereas the binary load needs no delays at all so loads quite quickly (1200bps)
After loading (watch the LED on the FTDI) it does need a reset to exit the loader.
I might revisit the hex loader another time but for now this is working well.
Update as usual is on the SC/MP page
Cheers
Phil

26th Aug 2023, 9:22 pm	#1
Phil__G Heptode Join Date: Mar 2011 Location: North Yorkshire, UK. Posts: 920	Tiny SC/MP system !!! I was looking at the memory expansion PCB that I'd used on the latest MK14v6, and started pondering... it has a scamp, rom, ram, a gal address decoder... its pretty much a complete computer so I thought maybe you could run Kitbug on it, with 1k rom and 3k ram, have the gal invert the flag 0 serial output... the tinyest kitbug machine! Well, I tried it and yes its now running Kitbug standalone! Its actually the eprom image I did for the Aitken machine, so there are a few features beyond the original NS Kitbug - and (for now) it has the famous bit7 serial bug which I'd forgotten about. The crystal is under the sc/mp and theres a reset cap etc added. Presently trying to port KitbugPlus but I used a lot of PICL specific code in there and I cant remember what I did... also Karen reduced GECO and PUTC to single byte pseudo-ops, when i expand these back to sc/mp code the monitor is 60 odd bytes larger and wont fit in the 1k... the gal presently splits it 1k rom 3k ram so I'll have to expand the rom area to get kb+ in there... Just a bit of timewasting fun rather than doing my chores... Cheers Phil Attached Thumbnails Last edited by Phil__G; 26th Aug 2023 at 9:29 pm.

27th Aug 2023, 12:52 am	#2
Mark1960 Octode Join Date: Mar 2020 Location: Kitchener, Ontario, Canada Posts: 1,200	Re: Tiny SC/MP system !!! Not sure what you connected to the gal but it could probably also latch the upper bytes of the address and run NIBL. I was thinking earlier that your MK14 was only being used as a keyboard and display.

27th Aug 2023, 10:40 am	#3
Phil__G Heptode Join Date: Mar 2011 Location: North Yorkshire, UK. Posts: 920	Re: Tiny SC/MP system !!! I think you could Mark but I've only ever done simple gal equations. There are plenty of wincupl examples but I havent found much using just eqn2jed, I need to buck up and learn wincupl A wierd problem delayed the project for an evening - with /hold, cont & /busrq all needing to be held high I commoned them together and used a single 1k pull-up. It didnt run and I found the commoned inputs tested low, even with the pull-up. As with many simple sc/mp designs I changed /nbreq to its own pullup and wired cont and /hold to vcc, and it sprang into life. I couldnt find anything in the datasheet that would explain this (?) unless one of them does something during startup, maybe bus arbitration or something. Or if cont or /hold pull a lot of current. It was only an experiment for fun, but its encouraged me towards a 'proper' sc/mp board Cheers - Phil Last edited by Phil__G; 27th Aug 2023 at 10:45 am.

27th Aug 2023, 12:16 pm	#4
Timbucus Octode Join Date: Mar 2019 Location: Barry, Vale of Glamorgan, Wales, UK. Posts: 1,349	Re: Tiny SC/MP system !!! Cracking idea Phil...

27th Aug 2023, 1:29 pm	#5
TonyDuell Dekatron Join Date: Jun 2015 Location: Biggin Hill, London, UK. Posts: 5,068	Re: Tiny SC/MP system !!! NBREQ is a bidirectional pin. It might well pull low momentarily after reset, and if that then asserts NHOLD and deasserts CONT it is quite likely the thing will not run.

27th Aug 2023, 3:27 pm	#6
Mark1960 Octode Join Date: Mar 2020 Location: Kitchener, Ontario, Canada Posts: 1,200	Re: Tiny SC/MP system !!! As Tony said, NBREQ is both an input and an output. It is pulled low by the 8060 at the start of every bus access. I think once the bus access is started CONT will be ignored, but NHOLD will make it wait at the end of the bus cycle and never finish.

27th Aug 2023, 4:34 pm	#7
Michael Haardt Tetrode Join Date: May 2021 Location: Titz, Germany. Posts: 71	Re: Tiny SC/MP system !!! I would welcome your spiced up version of Kitbug for native hardware. The bit 7 fix is simple: Add this in GECO towards the end: CAS DLD -1(P2) ; DECREMENT BIT COUNT JNZ $LOOP ; LOOP UNTIL 0 + LDI 045 ; DELAY BIT TIME FOR MSB + DLY 1 CSA ; SET STOP BIT ANI 0FE

27th Aug 2023, 7:14 pm	#9
Mark1960 Octode Join Date: Mar 2020 Location: Kitchener, Ontario, Canada Posts: 1,200	Re: Tiny SC/MP system !!! It would be nice if you could make it compatible with the single step circuit of the revised MK14 monitor and include coolsnaz fast loader.

27th Aug 2023, 9:05 pm	#10
Phil__G Heptode Join Date: Mar 2011 Location: North Yorkshire, UK. Posts: 920	Re: Tiny SC/MP system !!! Replicating the single-step circuitry in the gal is beyond me Mark I'd intended a hex loader but theres plenty of room for the fast-loader too Might not be soon though Cheers Phil

28th Aug 2023, 1:38 am	#11
Mark1960 Octode Join Date: Mar 2020 Location: Kitchener, Ontario, Canada Posts: 1,200	Re: Tiny SC/MP system !!! I was only thinking it would be nice to have the software support for the single step in your version of the monitor, I hadn’t considered trying to put that in the gal. I use that part of the MK14 monitor to release then next processor on the multiprocessor. I guess the fast loader might not make much sense either, you have a terminal emulator connected so you can just send a file direct from the terminal if it can load hex files.

30th Aug 2023, 10:12 am	#14
audiokit Triode Join Date: Jan 2021 Location: Hulst, Netherlands. Posts: 35	Re: Tiny SC/MP system !!! Hello Phil. Wow, that was a quick one after all! congrats and I will see if I can try it out soon. Indeed much better then the original kitbug which is very limited in its use.

30th Aug 2023, 4:06 pm	#15
Phil__G Heptode Join Date: Mar 2011 Location: North Yorkshire, UK. Posts: 920	Re: Tiny SC/MP system !!! Thanks Benny, I'd be interested to hear how you find it, presently it needs one-and-a-quarter kilobytes but if you allow 2k then we'll have room for updates such as the hex-loader which has to be the next priority I'm really enjoying the novelty of this tiny board, about 60mm square, and being able to change the address decoding at will is great for experimenting (within the 4k page of course)

1st Sep 2023, 10:11 pm	#17
Phil__G Heptode Join Date: Mar 2011 Location: North Yorkshire, UK. Posts: 920	Re: Tiny SC/MP system !!! I did a brief document for the project, http://philg.uk, bottom of the SC/MP page If anyone facies a go I have a few pcbs and can do a programmed GAL at cost, no profit Cheers Phil

2nd Sep 2023, 1:04 pm	#18
Realtime Hexode Join Date: Jan 2021 Location: Ashford, Kent, UK Posts: 261	Re: Tiny SC/MP system !!! Nice description of the project - very easy to follow. Might benefit from including a memory map. I expect that info is easily available else where but keeps it all together. I'll p.m you regarding a PCB and GAL in due course - another project to add to the ever growing list

2nd Sep 2023, 6:25 pm	#19
Phil__G Heptode Join Date: Mar 2011 Location: North Yorkshire, UK. Posts: 920	Re: Tiny SC/MP system !!! Thanks Ian - updated a few minutes ago.

2nd Sep 2023, 10:48 pm	#20
Phil__G Heptode Join Date: Mar 2011 Location: North Yorkshire, UK. Posts: 920	Re: Tiny SC/MP system !!! KitbugPlus now has a Serial loader, using the command Sxxx where xxx is the load address, and then sending a bin file using Teraterm (tick the bin option on the file, send screen) Its a binary loader cos in working on Intel Hex I was having to use silly long delays whereas the binary load needs no delays at all so loads quite quickly (1200bps) After loading (watch the LED on the FTDI) it does need a reset to exit the loader. I might revisit the hex loader another time but for now this is working well. Update as usual is on the SC/MP page Cheers Phil Last edited by Phil__G; 2nd Sep 2023 at 11:03 pm.