Jump to content
NIAD

ADAM Maintenance #02

Recommended Posts

I was talking with a fellow AA'er recently about his newly acquired ADAM Computer System and he mentioned the possibility of purchasing a 64K Memory Expander or piggybacking the extra RAM onto the already existing memory chips of the ADAM Circuit Board (he recalled that DoubleDown had done this and reported on his success with the procedure a number of years ago). So after a little research looking thru the old "Expandable Computer News" newsletters on Joe B.'s terrific site (link in footer of my message), I finally came across the article that was written by John Moore all the way back in 1987. So here it is...

 

Expand Your Memory



by John Moore

 

While there is a good number of 64K memory expansion boards available, the dedicated "hardware hacker" can add extra memory to his or her ADAM for about $10. Interested? First, remember that any changes inside ADAM will void any warranty you may have left. Since we have no control over it neither the author nor ECN may be held responsible for the results of your work. This modification requires good soldering skills, experience in working with circuit boards and with integrated circuits and a degree of patience.

 

:arrow: First you will need the raw materials! 8 - 4164 dynamic RAM memory chips (200 nanoseconds a less), and about a foot of fine insulated wire. The chips are widely available for about $1.50 each - check the Computer Shopper.

:arrow: Open your ADAM and work your way to the bottom board. This is the one with the expansion connector and the three expansion slots on it. The memory chips are above and to the right of the connector marked "J5." This is Slot #3 - the place where your 64K Ram card would have been plugged. The memory chips themselves will be numbered in various ways, but will most likely have 4164 somewhere in there. On my board, the chips are labelled "TMS4164-20NL." The 20NL means 20 nanoseconds. Notice that the locator "notch" on the chips goes toward the back on the back row and toward the front on the front row (THIS IS VERY IMPORTANT)!

:arrow: Now, prepare the expansion chips. Here is the way the little "bugs" are numbered. If you sit the IC on the table in front of you so that the "notch" points to your left, the bottom left pin is #1, the bottom right is #8, the top right is #9, and the top left is #16. On each of your eight chips, carefully bend pin #15 up so that it is vertical (or nearly so). Do this carefully so that you don't break a pin. If you do, that chip is useless!

:arrow: Now place one of the new 4164 chips on top of an existing chip. Be certain that the locator "notch" on both chips face the same way! Next, very carefully solder each pin on the new chip to the corresponding pin on the chip beneath it. There is a disc capacitor (C2) on the front row that may be troublesome. Carefully bend it out of the way as you solder.

:arrow: You now have 8 new 4164 chips mounted •piggyback" on the old chips. Check your soldering very closely. You may well have created a solder "bridge" between pins. If you have, ADAM won't boot (but will otherwise be OK). Look carefully!

:arrow: The final step is simple. Take the fine wire and connect each of the pin #15's of the new chips to the others. Finally, connect those pins to R15. This is a small resistor coded yellow-brown-black located between Slot #2 and Slot #3. There are two of them. You want the one nearer the back of the board. The wire connects to the side nearest Slot #3.

 

If you have completed these steps properly, you are now finished. Reassemble your ADAM, but don't put all the screws back in yet. Connect all the peripherals, and boot the machine. If SmartWRITER comes up, you are probably OK. If you have AdamCalc or BACKUP+ v. 3.0, start them running. Both will check the presence of expansion RAM. If this test passes, you may consider the RAM functional. As one last check, boot CP/M and PIP something to Drive M:. The command PIP M:=A:PIP.COM[v] will copy PIP itself to the RAM Drive and will verify that an exact copy was made (the [v] switch). If the transfer goes OK - you're home free!

 

In my experience, the most likely trouble is the solder bridge between pins. Use no more solder than is necessary. If you get a bridge, the computer probably won't boot - not even SmartWriter. The good news is that this usually will not damage the chips. Once the bridge is cleared, everything will work fine.

 

If you don't have the necessary skills, check with a TV repairman or a Ham Radio operator in your area. The work is delicate, but not beyond the capabilities of the average technician. A side effect of this modification is that you don't need to add any extra suppression, since the busses on the main board have already been suppressed.

Share this post


Link to post
Share on other sites

It's not really that you are freeing up Slot #3 for anything else due to the fact that the only interface card that can be used in this slot is a Memory Expander. But, by performing the above modification instead of using a Memory Expander Card, there are a lot less things that can fail over time... the Expansion Slot, the PCB, the 2 memory expander logic/controller chips and either 2, 4 or 8 DRAM chips depending on the make of the Memory Expander (although the piggybacked DRAMs can always go bad!!).

 

For the DIY'er who likes to tinker, piggybacking is definetly the way to go as well as for those who are looking to expand the ADAM's memory and can't find a Memory Expander Interface Card... they are getting to be extremely rare.

Share this post


Link to post
Share on other sites

I was afraid you'd say that...that slot 3 is only for memory expanders.

 

I wonder what would happen if a 64k card was inserted into the slot with the piggy banked memory?

Would it read 128k or the adam wouldn't function..?

Share this post


Link to post
Share on other sites

I was afraid you'd say that...that slot 3 is only for memory expanders.

:D :D :D

 

I wonder what would happen if a 64k card was inserted into the slot with the piggy banked memory?

Would it read 128k or the adam wouldn't function..?

I can't really say how the ADAM would react, but I would venture a guess that you would get a blank screen... no SmartWRITER Word Processor (which a lot of people probably wouldn't mind :? ).

 

As far as Memory Expander cards, the largest that the ADAM can recognize/address is the 64K varity without some additional hardware. Once you go past this 64K expansion RAM threshold (128K all the way up to 2Mb), you need either a Parallel Interface Card with Memory Addressing capabilities or a Memory Addressor Interface Card in Slot #2. Then a jumper wire is used to connect the two boards so that the ADAM can recognize and address all this additional expansion RAM. Without one of these cards installed in Slot #2, any size memory expander will only be recognized as a 64K M.E.

 

BTW, a 64K Memory Expander is all that one will ever really need in order to use and enjoy all the 3rd Party/Homebrew software that was released over the years like ADAM Bomb I & II, Temple of the Snow Dragon, etc.

Share this post


Link to post
Share on other sites

Niad how do you install more than 128K of ram?

 

It seems that having RAM equal to or greater than the maximum disc capacity would be the best option. That way an entire disc could be copied to the RAM and a copy of the disc could be made without switching back and forth between the original and the blank disc. Make quick copies of games and programs with only one disc drive.

 

Also wouldn't having enough RAM to load the entire game/program decrease the wear and tear of the DDP or Disc drive, since the entire game/program to be loaded into the RAM at start up?

Share this post


Link to post
Share on other sites

Niad how do you install more than 128K of ram?

If you are talking about the piggyback method, I can't honestly say that it would be possible to piggyback another bank of DRAMs on top of the 1st piggybacked bank. If it was, I would have to assume that there would have to be another mod to get this third bank to recognize... see the post above detailing a Memory Addressor Card in Slot #2.

 

Now if we are talking a Memory Expander (M.E.) Interface Card that installs in Slot #3, there are very few of the larger M.E. cards(128K, 256K, 512K, 768K, 1MB and 2MB incarnations) available anymore, if at all. You could check with Bob S. (AA handle is Adamcon) to see if he or Rich Clee, in Toronto have any extras that they would be willing to sell or you will have to watch eBay very diligently, but even then the sellers usually don't know much about what they have... probably most come across these systems at flea markets or garage sales and buy them with the intention of flipping them to make a quick buck.

 

I was lucky enough to win an auction earlier this year from wouldn't you know it, a former NIAD member, that included a 256K M.E. along with a ton of other goodies and then in my talks with him, ending up buying the remaining large lot of ADAM gear he had.

 

It seems that having RAM equal to or greater than the maximum disc capacity would be the best option. That way an entire disc could be copied to the RAM and a copy of the disc could be made without switching back and forth between the original and the blank disc. Make quick copies of games and programs with only one disc drive.

 

It does make things nicer (less swapping) if you have a large M.E. or if you have two drives so that one is the source and the other is the destination, be it 1 Disk & 1 Data Drive, 2 Disk Drives or 2 Data Drives. If you are making disk copies, I would recommend putting a PC to work using MS-DOS and DiskCopy to save wear and tear on your ADAM and ADAM drives... this is what we used to do to make all our copies back in the day. But here again, if you don't have two disk drives in the PC, you will be swapping disks as well.

 

Also wouldn't having enough RAM to load the entire game/program decrease the wear and tear of the DDP or Disc drive, since the entire game/program to be loaded into the RAM at start up?

 

Yes, that would be beneficial, but there are very few programs that were made over the years that offer the option to be copied onto a Memory Expander and then run from there without further need for the Disk or Data Pack. Some titles that come to mind that offer this option are ADAM Bomb I & II and Temple of the Snow Dragon. None of the Coleco made Super Games can be copied to a larger Memory Expander and run as you suggest... this is just how they were programmed.

 

There were two companies, Walters Software and Digital Express, who wrote some very good Memory Expander/RamDisk utilities that when used correctly allowed one to copy SmartBASIC v1.0 & v2.0, ADAMCalc, SmartWRITER and some other Coleco productivity software to a large Memory Expander and then switch instantly between them as if you had a hard drive. But unfortunately, nothing was ever done as far as patching the Super Games to work like this.

Share this post


Link to post
Share on other sites

If you have never visited Geoff Oltmans website detailing the ADAM and ADAMem SDL, the following details he provides on the ADAM are very interesting and may surprise a few people:

 

ADAM System Overview



by Geoff Oltmans

http://bellsouthpwp2.net/o/l/oltmansg/adam/active.html

 

The ADAM is actually a very well-conceived system. Manufactured by Honeywell for Coleco, it shows a few of the features that you would expect from a large computer system, rather than a home computer. The ADAM consists of a base computer system, and a collection of smaller computers (microcontrollers) that control the operation of the various peripherals connected to the machine. Most devices are connected through ADAMNet, a "high-speed" serial communications port, similar to the new USB ports found on many new PCs.

 

System Features:

 

- CPU: Zilog Z80A 3.58 MHz (NTSC color clock speed, PAL differs)

- Memory: 64K Base Memory. Expandable to 128K OEM, or 2048K third-party

- Secondary custom chips: MIOC (Memory Input/Output Controller) - controls generation of 8th bit DRAM refresh as well as bank switching and DMA. Master 6801 - Controls ADAMNet, allows devices to do DMA transfers with system memory.

- Video Display Processor: TMS9928 - Same family as used by TI 99/4A

- Video RAM: 16KB

- Colors: 15 with 1 transparent color for video overlay

- Sprites: 32 sprites, 4 visible sprites per scanline, with collision detection

- Screen Resolution: 256x192

- Sound: TI SN76489AN Sound/Noise generator. 3 voice square wave generator and one noise generator.

- Expansion Slots: Three internal expansion slots.

- Storage: Digital Data Drive or Floppy Disk. Third party floppy and hard drive systems available. Base system included one DDP Drive with room for another drive in the system's case. On the DDP Drive, up to 256K per DDP, unexpanded floppy drives use SSDD floppies for 160K storage.

- Operating Systems: OS7 (ColecoVision), EOS (ADAM), and CP/M

 

The thing that really makes the ADAM stand out from other home computer systems of the time is ADAMNet. ADAMNet was a 62.5k bps synchronous serial port, which supports up to 16 devices. The ADAMNet layout planned by Coleco included DCBs (device control blocks) for 2 printers, 2 DDP Drives, 4 disk drives, 1 modem, 1 hard disk drive, 1 80 column display adapter, as well as some other devices (see the EOS Programmer's Manual for more information). Another nice feature of ADAMNet was the ability of devices to perform DMA transfers to system memory. This freed the computer to run part of a program, while allowing the system to load the next part of the program. This is noticeable in several games, such as Super Buck Rogers. The player is allowed to play the game the whole time that additional parts of the game code and graphics are loaded into memory, all done transparently to the user. In addition, ADAMNet allows for up to 4GB(!) storage devices. No joke. Not bad for a home computer from 1983.

 

The operating system that ties this all together is EOS (Elementary Operating System). Please see the EOS Programmer's Manual for programming information and overview.

 

So in essensce, most of the hardware add-ons were planned to work off of ADAMnet... daisy chained off of one another like a modern USB Hub provides. The only two hardware items that were originally planned to be installed in an expansion slot were the Memory Expander (Slot #3) and a Language Card (Slot #2) for systems sold in foreign countries. If you ever come across a Language Card, you have yourself an incredibly rare item! Coleco eventually canceled the external ADAMnet 1200 Baud Modem and went with the internal 300 Baud Modem (Slot #1).

 

On the other hand, all 3rd Party/Homebrew hardware add-ons ended up using the 3 expansion slots or the expansion bus (with the exception of Micro Innovations line of Floppy Drives which used ADAMnet and a couple ADAMnet Hard Drives that were made) for the simple reason that it was cheaper and easier route to take than an ADAMnet device.

Edited by NIAD
  • Like 2

Share this post


Link to post
Share on other sites

I know this is an old thread but if anyone out there has the knowledge can you use TMS4164-15NL instead of TMS4164-20NL ram chips.

It seems everyone on EBAY is screaming vintage again and overpricing these.

And the 15NL's are reasonable.

Share this post


Link to post
Share on other sites

In theory seems like they should be fine... I would also be curious if anyone tries it ;)

 

Share this post


Link to post
Share on other sites

I have a few ADAM's and I just picked up enough Memory for eight CPU's
I am waiting now for my eprom programmer so I am also going to update all of them to Rev80 or better.
I also plan to have a working Digital Data drive and an internal power supply.

I may also put in an Arduino Based SD Floppy Emulator
I can add an HDMI upscaler but it's only changing the regular composite out and does not improve it.
It does however allow you to connect it to a modern TV through an HDMI port [email protected]

So it will be an 80k Console, Keyboard and one controller completely updated.

As soon as they are all together I am putting them on the market.
PM me if you are interested.

Edited by Mike Harris

Share this post


Link to post
Share on other sites

Someone out there knows a heck of a lot better than I do being I am like an intermediate newbie.

Underneath the later ADAM R80 Eproms is a piece of film with a pin on each end.
I suspect they are a modification to use newer types of chips but can someone tell me what they really are and what they are used for.
 

Edited by Mike Harris

Share this post


Link to post
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

Loading...

  • Recently Browsing   0 members

    No registered users viewing this page.

×
×
  • Create New...