More attic finds

[Phil__G]

I'm having to have a new boiler, everything has gone wrong and I'm having to clear my loft to get to the gas pipes. Sorry no ZX81s but some long lost stuff, remember Karens "Kansas City" Tape thread?
https://www.vintage-radio.net/forum/...d.php?t=169317

Well I found my 40-year-old Cottis Blandford cassette interface, last used for chatting via Packet Radio using the 'Cambridge' system. This was a BBC Micro-specific program using the inbuilt tape interface of the Beeb, and written in a mix of BBC Basic and 6502 code, so, being hardware-dependent, was exclusive to Beeb users.
As far as I'm aware I was the only one chatting with something other than a Beeb, I wrote a Z80 assembler version of the Cambridge system for the CP/M Bigboard and used this very Cottis-Blandford cassette interface. It still has the PTT relay mod and transceiver mic & speaker plugs.

Next I found a box of 6 or 7 "Quid Boards"
Around 1985 ish our local surplus dealer (N R Bardwell, Sheffield) was selling for £1 a metal cased Z80 board with 64k of dynamic, 2k of battery backed static, 2x empty 24pin eprom sockets, a power supply and 3 serial ports . The lads at work bought loads at the time and we named it the Quidboard. Me & a pal reversed and documented it and I patched Demon to run on it.
They were great for interfacing two different serial items, like my Fido BBS node and my ham radio AX25 packet TNC. I still have all the documentation to hand!

Ups and downs however, I also found our wedding cards, Pol's doll collection, lots of personal stuff that was difficult even to handle. Its been 5 years since I lost Pol and I miss her terribly.

To finish on a positive, (not really, theres loads more up there...) there was loads of Scalextric and Hornby 00 track and models to sort through, my old homebrew synthesizer comprising bits from Practical Electronics, ETI & Elektor, plus a few 'Dewtron' synth modules. The hours that went into that synth! It now comprises mostly of empty 741 sockets, where I've occasionally 'borrowed' one over the years!

AND

... highlight of the dig... my old Elekterminal and Cherry keyboard!!!
I just need to find a composite monitor, I'm sure there is one...

Cheers
Phil

[SiriusHardware]

Phil, very sorry to hear about your partner. My Dad has lost not one but two of his partners, one of them my mother, both far too early.

As to your technical finds, keep them coming. I notice your interesting 'quid board' has what looks like a NiMH battery on it, I would strongly suggest you desolder or snip that off and hurl it as far away as possible before it goes bad and eats the PCB tracks and component pins around it. There are too many old bits of otherwise functional retro kit being silently killed by rotting on-board batteries. I nearly lost my Maplin Z80 CPU kit board to that same menace.

[Phil__G]

Thanks SH that is appreciated.

If anyone would like a Quidboard just shout, spec in the post above. I'll probably only keep a couple

I haven't found the one with the Demon 2716 yet, if not I'm sure I've a copy somewhere in the stash. I dont have a Z80 development system now, the last was an Eaca Genie!

[Timbucus]

Sounds like a great mixed haul - memories can be both bittersweet as well though so thanks for sharing with us - looking forward to pictures of the Elekterminal working

Stop offering me things that sound fun to play with... I am a sucker for Z80 and one of those looks like it might make a better more contemporary card for my Z80 development system - https://www.youtube.com/watch?v=G_iBL94jGdw - that has what seems to be a serial driven Cassette interface in it...

Z80 dev systems are easy now - there is even the z88dk compiler for PC's that can do mixed C and ASM and target most Z80 systems...

[Phil__G]

It will probably cost no more to send a couple Tim if you PM your address please


More rummaging, I've just found an eprom & chipstash with a National 87P50 and also found a complete Tandy TRS80 model 1 !

[SiriusHardware]

Oh my, we knew a posh kid (one of probably less than 10 on Tyneside) who had a fully equipped TRS80 1 with dis(k) drives. Fond memories of playing 'Asylum' and 'The Count'.

[electronicskip]

Originally Posted by Phil__G

It will probably cost no more to send a couple Tim if you PM your address please


More rummaging, I've just found an eprom & chipstash with a National 87P50 and also found a complete Tandy TRS80 model 1 !

Many fond memories of playing with a TRS80 in Radio shack/Tandys on a saturday when my mum went shopping, and leaving rude scrolling messages on the screen!! hahaha .

[clockman]

I have two Amstrad PCW 8256 Word processors if any body wants them collection only TAB

[Timbucus]

Originally Posted by electronicskip

Many fond memories of playing with a TRS80 in Radio shack/Tandys on a saturday when my mum went shopping, and leaving rude scrolling messages on the screen!! hahaha .

Keep digging - love your finds. The TRS80 Model 1 was the first machine I wrote software on for someone else - my RE teacher lent me his personal one so I could write a CESIL interpreter so the other kids in the after school Computer club could type in during class rather than send them off for punching. The maths teacher had lent me his ZX80 manual before that so I could learn BASIC faster. The club (which in real terms meant me) were the only ones allowed to use the 380Z and the teletype (sum total of equipment available) after school.

[Phil__G]

...a badly home made AY-3-8500 Pong game from (guess) around 1980?

The TV modulator has throwing a wobbler though, it should be ch36 and my modern TV could only find a fuzzy image near ch25. Its built on what I think is an ETI magazine pcb

[acollins22]

That looks brilliant.

Back in the day Everyday Electronic published a design for a TV game built on a single CMOS chip. If I remember correctly it was for a motorcycle stunt rider game and the chip was about £25 at the time.

I fancied giving it a try but didn't want to risk that kind of money on a CMOS chip.


Cheers,

Andy.

Originally Posted by Phil__G

...a badly home made AY-3-8500 Pong game from (guess) around 1980?

The TV modulator has throwing a wobbler though, it should be ch36 and my modern TV could only find a fuzzy image near ch25. Its built on what I think is an ETI magazine pcb

[Timbucus]

One of my Christmas presents was a kit built one of those in the late 70's. My Dad was doing an engineering course at what is now Cardiff Met (was the Polytechnic) and he had to take it into the lab to find the fault. All done in secret in our shared Electronics workshop in the Attic

By the way the Z80 boards arrived, thank you so much - very interesting Z80CTC we have just had one of those implemented on the Spectrum Next. Just need to work out how they work and get that Battery removed before we have a rotted pcb!

[Station X]

Originally Posted by Phil__G

...a badly home made AY-3-8500 Pong game from (guess) around 1980?

Funnily enough only yesterday I unearthed an unused AY-3-8500 IC with a matching DIL socket. I must have had it for at least 40 years.

[Phil__G]

Originally Posted by Timbucus

By the way the Z80 boards arrived, thank you so much - very interesting Z80CTC ... Just need to work out how they work ....[

Thanks Tim, I'll scan the notes I have, though theres not as much as I remembered... enough to get them going, memory map etc. You'll have gathered the CTC is used for clocking the serial. Just a shame theres no PIO.
I found a 2716 labelled 'Demon' but my eprom programmer (Wireless World SC80!) is out of action.
I'll make a new one, just for EEPROMS (no point in UV these days). Before I've always used a 4040 for the address counter in my programmers but with Mega 2560s available for £6 why bother
Cheers
Phil

[Phil__G]

Quidboard

Here you go:
The notes are rough and I dont remember details as it was 40 years ago...
Demon is patched but with very few comments... sorry!
Theres a good example 'Telbbs4.zsm' which is my telephone to AX25 PBBS interface which ran on a quidboard for many years until the RSGB objected and I was in trouble! That program shows SIO setup, CTC for the baudrates and using the 6116 static ram, the Quidboard is entirely memory mapped, no I/O at all. The 64k dynamic is in two 32k pages switched by RTS. Not sure if you can still find the ZSM assembler or if it would run under Windoze 10.
Cheers
Phil

[acollins22]

Thanks Phil,

That looks handy


Cheers,

Andy.

[Slothie]

I had a holiday job with Marconi between 6th form and university and spent some of that time programming a Tandy TRS80 model1 level 2. I basically wrote a terminal emulator (it had the expansion interface box) that would allow data from the connected mainframe/minicomputer to be captured and used in BASIC programs for display. Good times!
I loved that computer, although I thought thr PET had a slight edge. You hardly see model 1s these days, at least here in the UK, Those very 70s America lines bring back the nodtalgia!

[TonyDuell]

The TRS-80 model 1 was my second computer (my first was the MK14 of course) and I still have it (with an expansion interface and one floppy drive) I never could find the official RS232 card so I made a copy with a roadrunner wiring tool from the circuit diagram. Worked first time...

I was going to convert a 'spare' model 1 into a model 3, and managed to get 48K RAM on the CPU board and even to get it to run model 3 basic from ROM. I then went to a radio rally and bought a real model 3, so I never finished the conversion.

Still have the model 3, but I now use (seriously..) a model 4.

Having used both the TRS-80 and PETs (2001, 8032 etc) I much prefer the former. But it may be becuase that's what I grew up with.

I also like the Tandy Color Computer range (6809 based). They can run OS-9 which is multi-tasking and just about multi-user. The CoCo 3 (up to 512K RAM, 80 column video display, etc) was never sold in the UK even though there was a PAL-output version sold in Australia. But mine is the normal NTSC model, fortunately there's an RGB output connector.

[Phil__G]

I found the actual Quidboard used for my PBBS, there are a few simple mods, a piggybacked 1489 to allow DCDB to be sensed and a couple of RS232 pins held high, and a bigger heatsink! the thin grey twin is 'reset' extended outside the box. These pics might help Tim and Andy to decipher my cryptic notes a few posts up ↑

(the central orange wire that goes under the tantalum to the 8251 is original, not a mod)

[MrBungle]

I saw one of those boards whizz past on eBay recently and missed it thanks to an excessively long conference call. Kind of regretting that now. Looks like it had a lot of interesting possibilities.