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fabrice montupet

Multiple GROM simulator

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My 99/8 computer has a low serial number (#22), it didn't received the Pascal GROM/ROM Kit.
I would like to try this feature. As it will be difficult to find a ROM/GROM Kit, I would like to make my own. No chance for me to produce a GROM, so my idea is to make a hardware GROM simulator that will use EPROM chips and that will use the less component that it is possible to make smallest PCBs. The goal is to install onto the 99/8 motherboard
No need to reinvent the wheel. So, before starting the developpment,I would like to know if someone has already made a GROM simulator that has the abilty to manage 10 GROMs.
Of course, I read many years ago the excelent book of Mike Bunyard about the TI-99 hardware and I was very interested by the GROM simulator that he proposed. But it is only for a 6Kb GROM chip. It could be a start for build my own simulator .
It seems to me that an article about the GROM simulation has been published in the German TI-Revue but I haven't found it.

Do you have any information?

Thanks by advance

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THere are a numberr of options, including VHDL, Verilog, and C code (AVR). But, the big question is:

 

how many GROM bases? I assume 2 bases of 5 GROMs each, but perhaps I am wrong.

 

JIm

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I haven't begun the study of all the P-System GROMs. But, yes, 5 GROMs per base is normaly the norm.

 

I forgot to mention an important pre-requisite : Not to disfigure the 99/8, I will use only technology that was used in 1983 ( at the 99/8 period). So no Atmel and all other things like that.

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The maximum memory as shown in MAME:

 

https://github.com/mamedev/mame/blob/master/src/mame/drivers/ti99_8.cpp

 

Speech: TMS5200C, a rare variant of the TMS52xx family. Compatible to the
speech data for the separate speech synthesizer for the TI-99/4A.
Speech ROMs CD2325A, CD2326A (total 128K*1)

ROM: TMS4764 (8K*8 ), called "ROM0" in the specifications [1]
TMS47256 (32K*8 ), called "ROM1" [1]
TMS47128 (16K*8 ), "P-Code ROM" (only available in late prototypes)
See below for contents

GROMs: TI-specific ROM circuits with internal address counter and 6 KiB
capacity (see grom.c)
3 GROMs (system GROMs, access via port at logical address F830)
8 GROMs (Pascal / Text-to-speech GROMs, port at logical address F840)
8 GROMs (Pascal GROMs, port at logical address F850)
3 GROMs (Pascal GROMs, access via port at logical address F860)
(total of 132 KiB GROM)

RAM: 1 TMS4016 (SRAM 2K*8 )
8 TMS4164 (DRAM 64K*1)

 

(I HATE these silly smileys that show up e.g. when you have an 8 and a closing parenthesis)

Edited by mizapf
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The 99/8 P-System GROM Kit contains 3 PCB ("A" that contains 4 GROMs, "B" that contains 2 GROMs and "C" that contains 4 GROMs) So according to the PCBs configuration, I can see 3 GROM base.

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Oh! Interesting! I never saw that!
On the five or six 99/8 computers equiped with P-System that I know, I don't remember seeing one with piggy-backed P-System GROMs. All of them has the same kit (3 PCB totalizing 10 GROMs) pluggable on the motherboard.

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Whatever way they were organized, we have genuine dumps of a total of 22 GROMs from Ciro's console. Maybe he can have a look inside how they look like.

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I would be happy to see pictures of them.
I know that such boards have been made ("8GROM" is written on my 99/8 motherboard top silk, near board "A" location ) but I never saw them.

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It seems to me that an article about the GROM simulation has been published in the German TI-Revue but I haven't found it.

 

Do you have any information?

 

Hi Fabrice,

 

Did you already find the TI-Revue articles?

I found an article in TI-Revue 5/85, where Heiner Martin published his his GROM module (8k GROM + 8k ROM) schematics and the PCB.

Additionally there are articles in TI-Revue 6/87 (which resides in the magazine HCA). Reiner Zigler tells us there how to build a module expander (a small hardware which generates additional GROM base addres select lines) and how to expand the previously mentioned GROM module to 40k GROM.

Do you need these articles?

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from the TI-REVUE_1985-05

 

I have this ROM/GROM Cartridge, her some Picture

 

and it works fine :)

 

 

 

 

post-25642-0-03395400-1493760874_thumb.jpg

post-25642-0-93961500-1493760930_thumb.jpg

post-25642-0-96149000-1493760989_thumb.jpg

post-25642-0-08518100-1493761050_thumb.jpg

post-25642-0-11174100-1493761068_thumb.jpg

post-25642-0-43386000-1493761083_thumb.jpg

post-25642-0-92420800-1493761094_thumb.jpg

post-25642-0-63626700-1493761111_thumb.jpg

Edited by Flottmann1
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Hi Fabrice,

 

Did you already find the TI-Revue articles?

I found an article in TI-Revue 5/85, where Heiner Martin published his his GROM module (8k GROM + 8k ROM) schematics and the PCB.

Additionally there are articles in TI-Revue 6/87 (which resides in the magazine HCA). Reiner Zigler tells us there how to build a module expander (a small hardware which generates additional GROM base addres select lines) and how to expand the previously mentioned GROM module to 40k GROM.

Do you need these articles?

I have the TI Part from the German Magazin HCA as PDF Scan here

HCA_1987_8.pdf

Edited by Flottmann1
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Not to stray too far OT, but...it makes me wonder about the GROM box TI was taking around to state fairs back in the day. A fair number of unreleased module dumps came our way because they were being shown on these boxes.

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Not to stray too far OT, but...it makes me wonder about the GROM box TI was taking around to state fairs back in the day. A fair number of unreleased module dumps came our way because they were being shown on these boxes.

 

 

Ksarul is now in possession of the two that I had. I have pictures on http://www.hexbus.comof them :)

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I have two of the CEC9914 GROM boxes, along with one of the pizza-box GSIM devices (and a lot of disks for it), an EGROM Box, and a GSIM that was modified by TI to become a prototype Plato module. . .

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Thank you Flottmann1 :-)

I am going to read it with a great pleasure!

Sorry Fabrice, for my late response, but Flottmann was too "flott" (German slang word for hurry) for me (like back the years in school: "hmmm, hmmm, take me...! I know it better...")

:-)

 

If you still miss some information, just ask... I only have my weekends to be TI-active...

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