4K Basic Support Module

[RXB]

19 minutes ago, acadiel said:

Depends on how much you want to support.  This is a ROM and RAM discussion.  (This is based upon my understanding, and some may be incorrect, which I'll lean on the titans to help correct me if needed.)

 

TI made eight GROM addresses available.  GROMs 0-2 are the console, and 3-7 are available in the module.  From the TI Tech Guide:

GROM 0: >0000-17FF - console boot/OS
GROM 1: >2000-37FF - console TI Basic
GROM 2: >4000-57FF - console TI Basic
GROM 3: >6000-77FF - cart
GROM 4: >8000-97FF - cart
GROM 5: >A000-B7FF - cart
GROM 6: >C000-D7FF - cart
GROM 7: >E000-F7FF - cart

For the five GROMS in a cartridge, you can have up to 30K (if you use 6K GROMs) or 40K (if you use 8K GROMs.)

 

There are also 16 "sets" of the cartridge GROMs that can be used (i.e. "REVIEW MODULE LIBRARY").  16 that are decoded, 256 I think are technically capable.  >9800, >9804, >9808, etc.  up to technically >9C00.  

 

So, to me that means 6K * 5 * 16 = 480K of GROM in 6K increments, or 8K * 5 * 16 = 640K for all sixteen banks the stock console will recognize via Review Module Library.  Or, for the max of 256 - 6K * 5 * 256 = 7680K for 6K GROMs or 10240K (1M!) if using 8K GROMs.  Anything past 16 needs custom code.  These bases could also very well be GRAM.

 

 

 

 

 

 

 

NO ONE MAKES 6K chips so using 6K * 5 * 16 = 480K is just silly at best.

EVERYONE USES 8K Chips so you are way off 8K * 5 * 16 = 640K

 

I have no idea why people keep saying this as where the hell would you get 6K chips?

Does anyone even make them anywhere?

Why do people saying this silly stuff?

[Pheonix]

Ick... I wasn't very clear   I was asking how much RAM (be it RAM, GRAM, VRAM, etc..) could be mapped into the TI at once.  For example, could the full 32K expansion area (8K @ $2000 & 24K @ $A000,) be mapped out as cartridge RAM.  Could this, then, be expanded to include the Mini-Mem area (4K @ $7000.)  Would it be possible to play RAM/ROM banking tricks like other computers do (set a bit, and that bank becomes RAM, clear it to restore the ROM, etc...)  Of course, I'm already aware that these can be banked with like (multiple (G)ROMs banked into the same address, etc...)

[+acadiel]

14 minutes ago, RXB said:

NO ONE MAKES 6K chips so using 6K * 5 * 16 = 480K is just silly at best.

EVERYONE USES 8K Chips so you are way off 8K * 5 * 16 = 640K

 

I have no idea why people keep saying this as where the hell would you get 6K chips?

Does anyone even make them anywhere?

Why do people saying this silly stuff?

TI GROMs were 6K.  So, it's not silly.   It's the way they made them.

 

GRAM emulation extended this to 8K (PGRAM, GRAM Kracker, GROMulator, etc.)

 

I've never seen a 6K GROM malfunction from being extended to 8K - that's just 2K of empty nothing.  So, other than TI cheapening out by saving 2K of mask ROM space, I have no other explanation on why they did it that way.

[RXB]

6 minutes ago, Pheonix said:

Ick... I wasn't very clear   I was asking how much RAM (be it RAM, GRAM, VRAM, etc..) could be mapped into the TI at once.  For example, could the full 32K expansion area (8K @ $2000 & 24K @ $A000,) be mapped out as cartridge RAM.  Could this, then, be expanded to include the Mini-Mem area (4K @ $7000.)  Would it be possible to play RAM/ROM banking tricks like other computers do (set a bit, and that bank becomes RAM, clear it to restore the ROM, etc...)  Of course, I'm already aware that these can be banked with like (multiple (G)ROMs banked into the same address, etc...)

Cart RAM is only 8K at a time, meanwhile SAMS can to 4K, 8K, 12K, 16K, 20K, 24K, 28K or 32K switch of RAM at any time.

Which one appears more versatile?

[Pheonix]

I've seen circuit designs that used 3 2k chips as 6k ram banks.  I've also seen circuits where 8k chips were set up with parity control turning them to 7k chips.  Finally, GROMs are 6K standard.... OK, answered while I was typing.

 

If cart RAM can only be 4k then the Mini-Mem must overwrite part of its RAM, or hide it somehow (it's 4k battery backed RAM @ $7000-7FFF.)  Going to have to take a closer look at that.

 

[+acadiel]

19 minutes ago, Pheonix said:

Ick... I wasn't very clear   I was asking how much RAM (be it RAM, GRAM, VRAM, etc..) could be mapped into the TI at once.  For example, could the full 32K expansion area (8K @ $2000 & 24K @ $A000,) be mapped out as cartridge RAM.  Could this, then, be expanded to include the Mini-Mem area (4K @ $7000.)  Would it be possible to play RAM/ROM banking tricks like other computers do (set a bit, and that bank becomes RAM, clear it to restore the ROM, etc...)  Of course, I'm already aware that these can be banked with like (multiple (G)ROMs banked into the same address, etc...)

RAM addressable space (not including scratch pad) includes:

 

>2000->3FFF - Lower 8K memory expansion

>4000->5FFF - DSR space - things like the SAMS card can use windows in this to their advantage with bank switching

>6000->7FFF - Cartridge space

>A000->FFFF - upper 24K memory expansion (can also be bank switched with SAMS)

 

These are the other areas in the memory map:

>0000->1FFF - is the console ROM

>8000->9FFF - this is scratch pad RAM, the memory mapped devices (i.e. VDP, speech, GROM/GRAM, sound)

 

[+acadiel]

3 minutes ago, Pheonix said:

I've seen circuit designs that used 3 2k chips as 6k ram banks.  I've also seen circuits where 8k chips were set up with parity control turning them to 7k chips.  Finally, GROMs are 6K standard.... OK, answered while I was typing.

 

If cart RAM can only be 4k then the Mini-Mem must overwrite part of its RAM, or hide it somehow (it's 4k battery backed RAM @ $7000-7FFF.)  Going to have to take a closer look at that.

 

 

CART ram can live anywhere in >6000->7FFF, or 8K total.  Mini memory uses half for ROM and half for RAM of that 8K address space.

 

[Pheonix]

Looking at the cartridge pinout, starting to see the 8K limit.  It only has access to address lines 3-15 (missing 0-2.)  So, only 8K can be address at a time.  Using one address bit (A15 for example) could make the lower half access a ROM while the upper accesses RAM (for direct addressing.)   I never took such a close look at the pinouts   I'm gathering there's no way to tell the TI to map that 8K elsewhere then.

[+acadiel]

2 hours ago, Pheonix said:

Looking at the cartridge pinout, starting to see the 8K limit.  It only has access to address lines 3-15 (missing 0-2.)  So, only 8K can be address at a time.  Using one address bit (A15 for example) could make the lower half access a ROM while the upper accesses RAM (for direct addressing.)   I never took such a close look at the pinouts   I'm gathering there's no way to tell the TI to map that 8K elsewhere then.

The sidecar has all the address lines.  Ksarul and I have talked in the past about making an 'ubercart' expander that would be a passthru where we could fit regular or 'expanded' cartridges to hit all the data and address lines, as well as audio.  (It would have been backward compatible with regular carts, too.)  The intent was whatever 'cartridge' you plugged in there would have the buffer chips/etc that it needed onboard, and you could literally do anything you wanted with the cartridge - add RAM, whatever.. it would be an ultimate prototype jumping board for expansion.  It never got beyond the exploratory phase, in the meantime we got a 32K, TI PI, and SAMs that all use somewhat of a modular connection - we could probably easily build another 'module' on that if we wanted to.

[+acadiel]

Someone drove up the eBay auction at the last minute (m***n(285)) but I had bid quite high on the BSM - so it should be headed my way so we can compare true operation of Bob's module with the UberGROM adaptation that we're doing.

 

 

[Flottmann1]

if you bought the BSM,  I would like to send you a donation

Edited April 20, 2020 by Flottmann1

[+acadiel]

18 minutes ago, Flottmann1 said:

if you bought the BSM,  I would like to send you a donation

Thank you, Bernhard!

 

[+Ksarul]

That was a lot for that cartridge. I paid about that much for mine too, but it came with a fully stocked PEB (including a p-Code card), an Editor Assembler prototype, and a dozen or so random common cartridges.

[+acadiel]

I just dumped my 4K BSM (thanks, Bob!)  Here's the binary.  It's different from Ksarul's binary.

bsm_jon.bin