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Old 05-30-2010, 11:53 AM   #21
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Default Re: Homebrew Tandy 1000 PC replica

Quote:
Originally Posted by basman74 View Post
Ah, you mean the printer port LPTn right? Please tell me you're only going to use it for it's originally intended purpose?

Okay, okay, hint taken!

By far the quickest and easiest way for me to get an LPT (or perhaps other standard expansion possibilities, like game ports etc.) would be to implement it as a daughter-board. Would this suffice?


Regards,
Valentin
Intended purpose? Of course not :-) A daughter board would be fine as long as it is not bulky. The parallel port should be bog standard SPP. JMHO of course. I can see uses for Start Commander, 64HDD and others.
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Old 06-01-2010, 07:58 PM   #22
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Default Re: Homebrew Tandy 1000 PC replica

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Intended purpose? Of course not :-) A daughter board would be fine as long as it is not bulky. The parallel port should be bog standard SPP. JMHO of course. I can see uses for Start Commander, 64HDD and others.
@redrumola,

Actually, one of the other 'unintended uses' I have in mind for the printer port is to use it with one of those 3-axis CNC parallel port interfaces. Already have software that potentially could run quite happily on the board.. but cannot update the LPT data output because
'You've attempted to access I/O register 378hex which is currently just a silly byte variable in memory, please check your address value and try again!'

Regards,
Valentin

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Old 06-01-2010, 10:40 PM   #23
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Default Re: Homebrew Tandy 1000 PC replica

Keep up the good work.
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Old 07-01-2010, 04:40 AM   #24
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Default Re: Homebrew Tandy 1000 PC replica

Well, given it's been a month since my last post so I thought I'd add a little update

After some more prodding through my emulator firmware, I managed the following enhancements to the 'virtual PC core'

1.) I added the once-popular 320x200x256 VGA/MCGA 'chunky mode' (aka mode 13h) to the list of supported graphics modes into the emulated BIOS and display controller. The only real restriction here is color palette being 'fixed' at 256 colors (output DAC assignment is 3/3/2-bits R/G/B respectively) and even the order of those fixed positions cannot be altered (at this time). That said however, it works and as a result some VGA games now also run in addition to Tandy Graphics/CGA supported games. Screenshots:

Elite Plus -
Title Screen
Player Screen

SU-25 Sturmovik flight sim demo -
Player Screen

Gobman (PacMan clone by filipe mateus) -
Title Screen
Player Screen

'SLIQ' from the PC demoscene era -
Utah Teapot

To allow some of the games to run at an acceptable speed, I decided to push the virtual system to it's highest possible limit on this 8-bit MCU made the core run to an equivalent speed of 1075 v1.1 Dhrystones (i.e. going into 80286 country..). This was achieved using some inelegant display hacks and an overclocked core.. Using SRAM instead of SDRAM for system memory should fix this problem and also take the system to say, well beyond 3000 Dhrystones without overclocking.

QBASIC compiled programs now run quite happily on this thing, but the speed of some runtime files, particularily those needing FPU support isn't blistering (the 'SLIQ' demo for example runs but is terribly slow, mainly for this reason). I've had more successes speed-wise with the C/C++/Assembly demos.

2.) Parallel port daughtercard: The artwork for this is also ready, which will use a CPLD (view artwork), though I cannot build it until I also do the artwork for an SRAM version of the mainboard (which will include an expansion header for the daughtercard).

Well, that's it from me for now.. I hope to put up another Youtube video demo on the VGA-related stuff shortly.

Cheers and enjoy!

Valentin

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Old 07-01-2010, 06:41 AM   #25
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Default Re: Homebrew Tandy 1000 PC replica

@Valentin

Thanks for the update! About time to go into mass production soon?
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Old 07-01-2010, 03:03 PM   #26
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Default Re: Homebrew Tandy 1000 PC replica

Congratulations on your project. In the late '80s and early '90s I managed a Radio Shack franchise (Delmar Co., Middletown DE). The 1000s were an interesting series with a lot a varieties. The original was a desktop with a separate keyboard (basically a slightly improved PCjr clone), one later model was a console (rather amiga 1200 like) with MS-DOS in ROM.
I remember a later pizza box style 1000 as having the first 386SX processor that finally allowed the 1000s to run Windows.

BTW - I held on to some 1000 keyboards for the longest time because those keyboard had excellent feel and feedback (similar to IBMs excellent keyboards).

And of course most Tandy computers were made in the US at a Tandy owned plant that tested the motherboards for 24hrs in a elevated heat environment before assembly.

Our company also did a lot with the Color Computer. Motorola's basic design relied on the processor to perform a lot of duties that other machines (from Commodore and Atari) had dedicated chips for. But the processor in the Color Computer (a 6809) was more powerful than competing 8 bit machines. We actually had a three terminal point of sales system running on one Color Computer. The Color Computer 3 was a little too much of an upgrade, too late. It's a shame Tandy didn't take that machine more seriously. At the end of its lifecycle, running under OS9 Level II with third party disk controllers (both floppy and hard drive) and memory expansions up to 2 meg it was a fun machine to work with.

When Tandy EOL'd the Coco, we brought out a 68000 based OS-9 computer that we sold for a few years (we even ported a GUI to it).
That project, the System IV, led to the 68030 powered System V.
If the owner of the company hadn't passed on, we were planning on releasing an accesory card the used two components from the Coco3 (the 6809 CPU and the GIME graphic and memory controller chip). This would have given us backward compatibility with Color Computer software.

I keep track of Tandy related retro projects as well as Amiga related projects. Although there is one difference. While Amiga users may consider themselves hobbyists, they have updated machines that can run modern software. Tandy hobbyists are restricted by the limited power of their machines and a lack of upgrade paths. Plus they haven't got the kind of useful software you see in the Amiga market.
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Old 07-01-2010, 10:27 PM   #27
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Default Re: Homebrew Tandy 1000 PC replica

Good work mate
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Old 07-02-2010, 12:26 AM   #28
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Default Re: Homebrew Tandy 1000 PC replica

Great work!!!! and since your in Oz i can buy one when they are ready and it won't cost me my arms to ship it here!
Great work looking forward to a finished product.
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Old 07-02-2010, 03:49 AM   #29
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Default Re: Homebrew Tandy 1000 PC replica

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Great work!!!! and since your in Oz i can buy one when they are ready and it won't cost me my arms to ship it here!
Great work looking forward to a finished product.
Thanks mate.

You know, I never seriously considered this thing to be a 'product' per se, more of a 'hobby project' that I show to the missus every now and then who tells me 'that's nice, dear.. '

Perhaps it is time that I did. Would be interesting to see just how much this thing would cost per-board for a production run of say a couple hundred or so units..


Regards, Valentin
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Old 07-02-2010, 03:53 AM   #30
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Default Re: Homebrew Tandy 1000 PC replica

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Good work mate
Thanks mate

Cheers, Valentin
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Old 07-02-2010, 04:32 AM   #31
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Default Re: Homebrew Tandy 1000 PC replica

@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

Last edited by basman74; 07-02-2010 at 08:43 AM..
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Old 07-02-2010, 04:49 AM   #32
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Default Re: Homebrew Tandy 1000 PC replica

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Originally Posted by redrumloa View Post
@Valentin

Thanks for the update! About time to go into mass production soon?
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

Last edited by basman74; 07-02-2010 at 05:16 AM..
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Old 07-02-2010, 07:19 AM   #33
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Default Re: Homebrew Tandy 1000 PC replica

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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'..

Last edited by basman74; 07-02-2010 at 07:25 AM..
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Old 07-22-2010, 07:53 AM   #34
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Default Re: Homebrew Tandy 1000 PC replica

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

Last edited by basman74; 07-23-2010 at 06:19 AM.. Reason: Tidy up
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Old 08-18-2010, 09:28 PM   #35
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Default Re: Homebrew Tandy 1000 PC replica

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
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Old 10-20-2010, 12:04 AM   #36
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Default Re: Tandy 1000 PC replica - Progress update

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
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