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Old 26th Nov 2022, 4:20 pm   #1
777xxxx
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Default Do any of the programs by Tim Gilberts, etc work with the mk14 with VDU emulator?

ive managed to get hold of a mk14 with vdu emulator that work but can only get one of the programs to work. image.hex. i tried invaders, clive, etc but these dont. the emulator os called Science of Cambridge MK14 Emulator by Paul Robson. the version is 1.9 (12-June-1998). i would post a link to it here but im not sure im allowed to.
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Old 26th Nov 2022, 6:30 pm   #2
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Default Re: Do any of the programs by Tim Gilberts, etc work with the mk14 with VDU emulator?

777xxxx, the problem you may be experiencing is that some of the software intended for the VDU Including invaders) writes to added memory mapped into the 0200-07FF area and the VDU is expected to be set up to display the contents of 512 bytes of that additional RAM. The question is whether your emulator (a) emulates RAM at those addresses and (b) can inform its 'VDU' to use those areas as screen RAM.
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Old 26th Nov 2022, 7:27 pm   #3
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Default Re: Do any of the programs by Tim Gilberts, etc work with the mk14 with VDU emulator?

According to the instructions it has this feature:

SC/MP memory expansion conversion made (so 200-7FF are all RAM)

and this is the switch:

-v turns the VDU on in text mode with 0B00 being the top page and
0F00h being the bottom page.

Maybe there is some thing wrong here?
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Old 26th Nov 2022, 8:32 pm   #4
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Default Re: Do any of the programs by Tim Gilberts, etc work with the mk14 with VDU emulator?

i think its ok to give a link to it as it is publicly available.

here:

http://www.dougrice.plus.com/mk14/mk14zips.zip

not sure how to change it, maybe it needs recompiling?

Last edited by 777xxxx; 26th Nov 2022 at 8:38 pm.
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Old 26th Nov 2022, 9:22 pm   #5
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Default Re: Do any of the programs by Tim Gilberts, etc work with the mk14 with VDU emulator?

Right, so that configuration is only compatible with 'Legacy' programs which were intended to be run on an MK14 which is fully expanded onboard to 640 bytes (of which 512 bytes is required by the VDU). It will not work with programs which use added RAM in the 0200-07FF area as screen RAM.

You need more than one -v switch, say -v1 for the existing configuration which should work with 'Legacy' software and a new setting -v2 which tells the VDU to render from 0200-02FF (top half of screen) and 0300-03FF (lower half of screen).

To be more like the real VDU you need to be able to specify the start address of any 256-byte page to be rendered to the top half of the screen and the start of any other 256-byte page to be rendered to the bottom half of the screen. (These addresses will always be on 256-byte page boundaries, for example 0200, 0300, 0400, 0500, 0600, 0B00, 0F00).
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Old 26th Nov 2022, 9:31 pm   #6
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Default Re: Do any of the programs by Tim Gilberts, etc work with the mk14 with VDU emulator?

If you are linking to something you created its better to attach files to your post as you might stop maintaining the link.

If you are linking to someone elses work I think you should link to their site, not just the files, as this gives people the opportunity to visit their site.
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Old 26th Nov 2022, 9:44 pm   #7
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Default Re: Do any of the programs by Tim Gilberts, etc work with the mk14 with VDU emulator?

The VDU has one-bit hardware inputs which control various aspects of its operation, such as whether the VDU renders the contents of the screen RAM to the screen as characters or graphic pixels, or whether the screen is shown in normal (white on black background) or inverse (Black on white background). The emulation should really have switches which can be used to set any of these 'control inputs' high or low.

There is also an output on the VDU called TOP PAGE which is in one state when the top half of the screen is being rendered and in the other state when the bottom half of the screen is being rendered. This is traditionally connected to one of the PS... inputs so that the top half of the screen and the bottom half of the screen do not show the same 256-byte block of memory.

For example to make the VDU show the contents of 0200-02FF on one half of the screen and the contents of 0300-03FF on the other half of the screen the page select (PS...) inputs would be connected like this:-

PS1 - to TOP PAGE
PS2 - High
PS3 - Low
PS4 - Low

PS1 is A8 of the base address for the VDU to use as screen memory so connecting it to TOP PAGE wiggles the base address between 0200 and 0300.
It would also be necessary to assert the SWAP PAGES control input to place 0200-02FF on the upper half of the screen and 0300-03FF on the lower half of the screen.

For legacy programs where you want 0F00-0FFF to be displayed on one half of the screen and 0B00-0BFF to be displayed on the other half of the screen, the connections for the page select inputs would be

PS1-High
PS2-HIGH
PS3-to TOP PAGE
PS4-HIGH

This wiggles the screen base address between 0F00 and 0B00, and this is the setup that your -v switch emulates at the moment.
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Old 26th Nov 2022, 10:17 pm   #8
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Default Re: Do any of the programs by Tim Gilberts, etc work with the mk14 with VDU emulator?

777xxxx, what (out of that zip archive) are you actually running? The .COM file? If so it looks as though that is hard coded to use 0F00-0FFF as one half of the screen memory and 0B00-0BFF as the other half of the screen memory. The only other options are to swap the upper and lower halves of the screen around with the -i switch and to render the content of the screen RAM as graphics rather than text with the -g switch.

To add to these options you would need to be able to read and understand the original source code, add additional switches to the options and recompile the code which must originally have been written to compile on a now ancient compiler. I don't know if anyone here has the wherewithal to adjust it to compile with a current 'C' compiler?
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Old 27th Nov 2022, 2:35 pm   #9
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Default Re: Do any of the programs by Tim Gilberts, etc work with the mk14 with VDU emulator?

Quote:
Originally Posted by SiriusHardware View Post
To add to these options you would need to be able to read and understand the original source code, add additional switches to the options and recompile the code which must originally have been written to compile on a now ancient compiler. I don't know if anyone here has the wherewithal to adjust it to compile with a current 'C' compiler?
Had a quick look, the source code in the zip archive doesn't seem to include the VDU emulation part, just the basic emulation capability. Well, I couldn't find any trace of the '-v' qualifier, or any code that looks specifically at changes to the 0xFxx, 0xBxx memory ranges.

That's not to say it wouldn't be possible to re-implement that part of the code fairly simply but it would be non-trivial.

I am kind of tempted but given I have an actual MK14 and an Ortonview its hard to overcome my laziness....
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Old 27th Nov 2022, 4:28 pm   #10
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Default Re: Do any of the programs by Tim Gilberts, etc work with the mk14 with VDU emulator?

Quote:
Originally Posted by Slothie View Post
Quote:
Originally Posted by SiriusHardware View Post
To add to these options you would need to be able to read and understand the original source code, add additional switches to the options and recompile the code which must originally have been written to compile on a now ancient compiler. I don't know if anyone here has the wherewithal to adjust it to compile with a current 'C' compiler?
Had a quick look, the source code in the zip archive doesn't seem to include the VDU emulation part, just the basic emulation capability. Well, I couldn't find any trace of the '-v' qualifier, or any code that looks specifically at changes to the 0xFxx, 0xBxx memory ranges.

That's not to say it wouldn't be possible to re-implement that part of the code fairly simply but it would be non-trivial.

I am kind of tempted but given I have an actual MK14 and an Ortonview its hard to overcome my laziness....

have a look in the mk14 folder. theres a com file in there that uses the -v switch, etc. but theres no source code in there for it. it runs in dosbox

Last edited by 777xxxx; 27th Nov 2022 at 4:54 pm.
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Old 27th Nov 2022, 5:07 pm   #11
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Default Re: Do any of the programs by Tim Gilberts, etc work with the mk14 with VDU emulator?

Quote:
Originally Posted by 777xxxx View Post

have a look in the mk14 folder. theres a com file in there that uses the -v switch, etc. but theres no source code in there for it. it runs in dosbox

it also says in the instructions in both the source folders that it includes a vdu. here:

''These are three ports of the MK14 "C" emulator. One is for Windows, two
are for DOS (one uses Graphics, one uses Text Mode)''
I know, I am just saying that in the actual source code the code for the VDU functions does not exist. In order to change anything, you need the source. Unfortunately in order to get the emulator to work with the VDU mapped to any other area it would require the program to be modified.

There are some sources for a windows 32 version. Its been over 30 years since I last wrote a windows 3 program, but I did have a look in there in case there was any code relating to the VDU I could see but to no avail. I haven't any fcility to run DOS/windows exes at the moment so I can't confirm but from the code it looks like it just shows the LED displays and interacts with the keyboard.

the source code in mk14_src.zip is version 1.0 (15 May 1998) (according to main.c)
The file MK14.TXT in mk14.zip that refers to VDU support refers to version 1.9 (12-June-1998)

So it looks like the source for the VDU version is not in the zip-of-zips.
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Old 27th Nov 2022, 5:11 pm   #12
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Default Re: Do any of the programs by Tim Gilberts, etc work with the mk14 with VDU emulator?

Quote:
Originally Posted by Slothie View Post
Quote:
Originally Posted by 777xxxx View Post

have a look in the mk14 folder. theres a com file in there that uses the -v switch, etc. but theres no source code in there for it. it runs in dosbox

it also says in the instructions in both the source folders that it includes a vdu. here:

''These are three ports of the MK14 "C" emulator. One is for Windows, two
are for DOS (one uses Graphics, one uses Text Mode)''
I know, I am just saying that in the actual source code the code for the VDU functions does not exist. In order to change anything, you need the source. Unfortunately in order to get the emulator to work with the VDU mapped to any other area it would require the program to be modified.

There are some sources for a windows 32 version. Its been over 30 years since I last wrote a windows 3 program, but I did have a look in there in case there was any code relating to the VDU I could see but to no avail. I haven't any fcility to run DOS/windows exes at the moment so I can't confirm but from the code it looks like it just shows the LED displays and interacts with the keyboard.

the source code in mk14_src.zip is version 1.0 (15 May 1998) (according to main.c)
The file MK14.TXT in mk14.zip that refers to VDU support refers to version 1.9 (12-June-1998)

So it looks like the source for the VDU version is not in the zip-of-zips.
yeah, thats right. did you have look in here?

http://www.dougrice.plus.com/mk14/

might be in there somewhere although i cant find it
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Old 27th Nov 2022, 5:33 pm   #13
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Default Re: Do any of the programs by Tim Gilberts, etc work with the mk14 with VDU emulator?

It's preliminary, but VDU support will be coming to MAME very soon. Hopefully for the end of December release.
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Old 27th Nov 2022, 5:34 pm   #14
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Default Re: Do any of the programs by Tim Gilberts, etc work with the mk14 with VDU emulator?

Quote:
Originally Posted by 777xxxx View Post
yeah, thats right. did you have look in here?

http://www.dougrice.plus.com/mk14/

might be in there somewhere although i cant find it
Theres another ZIP file mk14_src_sdl.zip that contains a different emulator, based on a Nascom/Z80 emulator but appears to link with the MK14/SC/MP emulator but that doesn't appear to have the VDU function either.....

There are fragments of other related programs scattered about, It's a bit like archeology.....

Beginning to think it might be easier to write one in Python from scratch....
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Old 27th Nov 2022, 6:00 pm   #15
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Default Re: Do any of the programs by Tim Gilberts, etc work with the mk14 with VDU emulator?

I'm relieved Slothie couldn't see anything relating to the VDU emulation in the source either, I thought that was just me.

I understand Paul Robson (original author of the emulator program under discussion) attended the RCF at the Centre for Computing History a few weeks ago, might he be amenable to requests for the source for the 'with VDU emulation' version? He makes it quite clear in the documentation that he has taken the development of the emulator as far as he intends to himself, but he does throw an olive branch in the form of an offer to help anyone who might be trying to port it to some other OS like Linux, so maybe the door is still slightly ajar. On the other hand this was so long ago that maybe even Paul himself no longer has the relevant source code.
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Old 27th Nov 2022, 6:04 pm   #16
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Default Re: Do any of the programs by Tim Gilberts, etc work with the mk14 with VDU emulator?

Quote:
Originally Posted by SiriusHardware View Post
On the other hand this was so long ago that maybe even Paul himself no longer has the relevant source code.
Some of the dates on the later source files are 2017, so it looks like he's been tinkering with it, unless that's just where files have been copied around.
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Old 27th Nov 2022, 6:09 pm   #17
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Default Re: Do any of the programs by Tim Gilberts, etc work with the mk14 with VDU emulator?

It sounds as though Pernod70 may have a fully functional modern emulator including VDU emulation by the end of the year, touch wood, but any such emulator will need to address this need to be able to point the VDU at different areas of MK14 memory to suit different use cases. Essentially, it needs 'switches' to either force the 'control inputs' to a specific logic state or to 'connect' them to the TOP PAGE logic signal.

Setting these up would be complicated for newcomers so maybe also have at least two, possibly more, preset onfigurations for commonly used setups like the ones mentioned in #7
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Old 27th Nov 2022, 6:15 pm   #18
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Default Re: Do any of the programs by Tim Gilberts, etc work with the mk14 with VDU emulator?

Quote:
Originally Posted by SiriusHardware View Post
It sounds as though Pernod70 may have a fully functional modern emulator including VDU emulation by the end of the year, touch wood, but any such emulator will need to address this need to be able to point the VDU at different areas of MK14 memory to suit different use cases. Essentially, it needs 'switches' to either force the 'control inputs' to a specific logic state or to 'connect' them to the TOP PAGE logic signal.
At the moment it's just rendering characters from 0200-03FF, but will be fully configurable when I'm done with it.
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Old 27th Nov 2022, 6:22 pm   #19
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Default Re: Do any of the programs by Tim Gilberts, etc work with the mk14 with VDU emulator?

Another point of info Pernod, that image posted in #13 looks quite vertically stretched so if it is within your power, try also to make the active area of the VDU display more or less square. Unless of course you took the shot with your phone in portrait mode, in which case ignore.

We'd better just let you get it all working first.

Last edited by SiriusHardware; 27th Nov 2022 at 6:30 pm.
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Old 27th Nov 2022, 6:55 pm   #20
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Default Re: Do any of the programs by Tim Gilberts, etc work with the mk14 with VDU emulator?

Quote:
Originally Posted by SiriusHardware View Post
Another point of info Pernod, that image posted in #13 looks quite vertically stretched so if it is within your power, try also to make the active area of the VDU display more or less square.
The screen snapshot is 128x256 pixels which assumes square pixels. The actual screen rendering stretches it to a 4x3 ratio.
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