Homebrew Tandy 1000 PC replica

[basman74]

Good work mate

Thanks mate

Cheers, Valentin

[basman74]

@iggy

Thanks for your reply and also for sharing your interesting first-hand account with us!

As you've stated the CoCo3 was indeed a much more powerful beast than the machine it replaced (Z80-based CoCo2, of which I owned a clone) and put it inline with the Tandy 1000 and it's 8088 CPU, which in terms of basic performance was in the same league as the 6809..

One thing that I didn't get about the CoCo3: It wasn't compatible with either MS-DOS or most of the CoCo2 related stuff, yet it was a really nice machine? Tandy obviously wanted to try and the market to a higher level in 8-bit computing circles methinks..

Totally did not know about the enhanced 68k CoCo derivatives (the machines you referred to as systems IV/V) Good to see your old company (Delmar Co.) picked up the ball and make their own advanced CoCo derivatives after Tandy pulled out of that market! Really fascinating stuff!


Regards,
Valentin

[basman74]

@Valentin
 
Thanks for the update! About time to go into mass production soon? :hammer:

Jim,

I've already begun the final assembly of some boards, though you'd probably laugh if you saw my initial assembly-line for the 'mass production' (gotta show a pic of that one!)

Hopefully once I have the emulation firmware finalised, there's not alot more that I would want to add to the SDRAM edition of the PCB. Please feel free to disagree, however..


Cheers,
Valentin

[basman74]

I've already begun the final assembly of some boards, though you'd probably laugh if you saw my initial assembly-line for the 'mass production' (gotta show a pic of that one!)

My in-house 'assembly-line'..

[basman74]

Progress update:

I have managed to add basic 256-palette DAC table support into VGA Mode 13h. Apart from correct colour representation, other cool things also now work, like colour cycling and video transitions/fading..

Of course, the table itself consists of 8-bit entries to match the video DAC on the board, so a conversion to/from 18-bit colour is performed before reading/writing to the table. While the conversion process is drastic to say the least, I think the result isn't as bad as one might imagine, though needless to say there's a noticeable difference.. I will leave it to others to comment on the visual improvement. Included are some screenshots of games after the inclusion of the palette DAC emulation:

Elite Plus -
 Title Screen
 Player Screen

SU-25 Sturmovik flight sim demo -
 Player Screen

Gobman (PacMan clone by filipe mateus) -
 Title Screen

Displaying a JPEG image of the prototype board using 'LXPIC' DOS image viewer  -
 Displayed jpeg file


Things to-do:
------------
1.) Test VGA output on as many LCD monitors as I can access, to ensure I got the timing right. Should work 100% on any old VGA CRT monitor however, as they are somewhat more forgiving..

2.) Finish the Keyboard and hard-drive controller emulation portions of the firmware and finalize details on a simplified expansion bus..


Cheers and Enjoy!

Valentin

[basman74]

Hi All,

After a few distractions, I finally managed to make a video of some early VGA games in action on the second prototype:

http://www.youtube.com/watch?v=diapn3Hkh1k

Note the specific color-cycling and video fade-in/out effects in most of the games demoed and also how slow Dune 2 runs on a (virtual) 10MHz 8088!


Cheers and enjoy!

Valentin

[basman74]

Hi All,

Well, after around 18 months part-time worth of stuffing about I finally got round to completing my own version of a tiny PC clone (well, the first version anyway..)

Piccies of the 'FLEA88' system box..

Front view:

Rear view:

Internal view:


Things added to the emulation firmware:
* Added virtual disney sound source, connected to the virtual LPT1 (look mom, no wires!) So now the PC speaker, Tandy Sound Gen. and Disney audio values are summed equally in firmware and sent out through the host audio DAC.
* Keyboard and mouse virtual interface improved considerably
* Int 10h video functions now largely complete, though some tiny quirks remain
* Hard disk write handler now complete so that high scores can now be saved (among other things), will need further testing
* Serial port COM1 now functional, albeit with basic support at the BIOS level only..
* CPU Trace Interrupt (01h) functionality added and fixed a stack (no pun intended) of CPU-related bugs..

Due to increasing time constraints, I've decided to keep the expansion possibilities to a minimum for the above showcase model.

Managed to get the firmware ready in time to showcase the system at our local (Amiga-oriented) computer user group over the previous weekend, where the response was quite positive overall.. No event pics unfortunately, as I had to leave far too early - oh well there's always next month..

Anyhow that's all from me for now - gotta get back to conqu... uh, I mean beta testing!


Cheers,

Valentin