Jump to content

Photo

Multiple GROM simulator


11 replies to this topic

#1 fabrice montupet OFFLINE  

fabrice montupet

    Chopper Commander

  • 174 posts
  • Location:Burgundy - France

Posted Thu Feb 16, 2017 10:59 AM

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
 



#2 brain OFFLINE  

brain

    Chopper Commander

  • 102 posts

Posted Thu Feb 16, 2017 2:10 PM

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



#3 fabrice montupet OFFLINE  

fabrice montupet

    Chopper Commander

  • Topic Starter
  • 174 posts
  • Location:Burgundy - France

Posted Thu Feb 16, 2017 3:00 PM

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.



#4 mizapf OFFLINE  

mizapf

    River Patroller

  • 2,157 posts
  • Location:Germany

Posted Thu Feb 16, 2017 3:09 PM

The maximum memory as shown in MAME:

 

https://github.com/m...vers/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, Thu Feb 16, 2017 3:11 PM.


#5 fabrice montupet OFFLINE  

fabrice montupet

    Chopper Commander

  • Topic Starter
  • 174 posts
  • Location:Burgundy - France

Posted Thu Feb 16, 2017 4:00 PM

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.



#6 mizapf OFFLINE  

mizapf

    River Patroller

  • 2,157 posts
  • Location:Germany

Posted Thu Feb 16, 2017 4:23 PM

If I remember correctly they piggy-backed GROMs.



#7 fabrice montupet OFFLINE  

fabrice montupet

    Chopper Commander

  • Topic Starter
  • 174 posts
  • Location:Burgundy - France

Posted Thu Feb 16, 2017 4:38 PM

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.



#8 mizapf OFFLINE  

mizapf

    River Patroller

  • 2,157 posts
  • Location:Germany

Posted Thu Feb 16, 2017 5:10 PM

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.



#9 Ksarul ONLINE  

Ksarul

    River Patroller

  • 3,847 posts

Posted Thu Feb 16, 2017 6:06 PM

They are stacked on both of my 99/8s. . .boards "A" and "C" have 8 GROMs each.



#10 fabrice montupet OFFLINE  

fabrice montupet

    Chopper Commander

  • Topic Starter
  • 174 posts
  • Location:Burgundy - France

Posted Fri Feb 17, 2017 2:25 AM

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.



#11 Tursi OFFLINE  

Tursi

    River Patroller

  • 4,453 posts
  • Location:BUR

Posted Fri Feb 17, 2017 11:25 PM

My AVR code can handle 15 (8k) GROMs in a single ATMEGA1284 (120k total). It's glueless - you can connect it directly to the GROM bus, and pretty easy to change the mapping for whatever layout you need.

http://harmlesslion....ftware/ubergrom

#12 fabrice montupet OFFLINE  

fabrice montupet

    Chopper Commander

  • Topic Starter
  • 174 posts
  • Location:Burgundy - France

Posted Sat Feb 18, 2017 6:58 AM

Your UberGROM using the ATMEGA1284 is a really a great work, but I wish my project uses more age-old components.






0 user(s) are browsing this forum

0 members, 0 guests, 0 anonymous users