PKG.SPARKMAN@MCC.COM.UUCP (02/17/87)
Randy, Please don't give up on pressing for answers about modifing your amiga 1000. You aren't being thick headed, others simply aren't listening (reading properly). I thought of the above expansions myself and hoped it would be discussed. As far as the power requirements goes, it seems that one could (In line with the daughter board idea) remove the 256K plug in module from the front of the amiga 1000, remove the 256K dram chips from the mother board, and use 1 meg dram chips to get 2 meg chip ram without changeing chip count. Yes I know the 1 meg chips are more expensive, but then you don't have to add a power supply (do you?) and it is simpler. So lets investigate (or explain why not) this daughter board for one meg chips agnes, paula, and any other sisters I forgot to mention. Aubrey Sparkman Everyone disclaims me. arpa: pkg.sparkman@mcc.com -------
cmcmanis@sun.UUCP (02/18/87)
In article <12279780357.24.PKG.SPARKMAN@MCC.COM>, PKG.SPARKMAN@MCC.COM (Aubrey Sparkman) writes: > Please don't give up on pressing for answers about modifing your amiga 1000. > You aren't being thick headed, others simply aren't listening (reading > properly). I thought of the above expansions myself and hoped it would be > discussed. Actually the schematics are really useful for trying to figure out what you can and cannot do with the Amiga internals. Easily worth the $20 Commodore is charging for them (they also include PAL codes). Basically, it isn't fruitful discussing expanding the 'chip' ram of the Amiga if one has no idea what the new chips will look like. As for adding internal memory that looks like 'fast' ram that is possible and documented in the latest RoboCity News (the FAUG newsletter) and in Amazing Computing I believe. > As far as the power requirements goes, it seems that one could (In line with > the daughter board idea) remove the 256K plug in module from the front of > the amiga 1000, remove the 256K dram chips from the mother board, and use > 1 meg dram chips to get 2 meg chip ram without changeing chip count. > Yes I know the 1 meg chips are more expensive, but then you don't have to add > a power supply (do you?) and it is simpler. Two problems here (certainly not fatal however) first there are only 18 address lines on the nose piece so you would have to put a couple of wires through the front, secondly if you replaced the 256K chips with 1Meg chips you would have 1 Meg. Now if you remove the nosepiece and replace the internal 256K chips with 1Meg chips (and add a couple of wires) you could have a 1 meg internal Amiga. And the power requirements would be relatively straight forward since replacing 512K of 256K rams (the nosepiece and the internal ram) with 1Meg of 1Meg chips is a net reduction in power required. > So lets investigate (or explain why not) this daughter board for one meg chips > agnes, paula, and any other sisters I forgot to mention. > Aubrey Sparkman As mentioned by others (including Commodore's engineering staff) you cannot increase the address space of the custom chips. You can add internal RAM expansions however the new memory would have to be allocated to the 'fast' RAM pool rather than the Chip ram pool. The only difficulties you will encounter will be the power requirements (avoidable with good planning), fitting the darn thing in there (have you taken off the lid to your Amiga?), and making sure the new memory resides in a compatible address space. Note that this is also true of the Amiga 2000 because it uses the same custom chips as the Amiga 1000 and they are limited to accessing 512K of 'Chip' ram. -- --Chuck McManis uucp: {anywhere}!sun!cmcmanis BIX: cmcmanis ARPAnet: cmcmanis@sun.com These opinions are my own and no one elses, but you knew that didn't you.
hedley@cbmvax.UUCP (02/18/87)
In article <12279780357.24.PKG.SPARKMAN@MCC.COM> PKG.SPARKMAN@MCC.COM (Aubrey Sparkman) writes: > >As far as the power requirements goes, it seems that one could (In line with >the daughter board idea) remove the 256K plug in module from the front of >the amiga 1000, remove the 256K dram chips from the mother board, and use >1 meg dram chips to get 2 meg chip ram without changeing chip count. >Yes I know the 1 meg chips are more expensive, but then you don't have to add >a power supply (do you?) and it is simpler. > All RAM is not created equal. I'm sure both of you have heard of "CHIP memory" and "FAST memory". "FAST" memory is memory that sits on the 68000 buss. It is not accessable by the custom chips. Its called "FAST" because the custom chips cannot lock the processor out of accesses to that memory. Therefore, even if the custom chips a blitting, and DMAing and just wreaking havoc on their buss, the processor can still purr along quite nicely. "CHIP" memory is accessable both by the processor, and the custom chips. This means, that under certain conditions (Hold and Modify mode for example ), the custom chips can prevent the processor from using this memory from time to time. Hence, code running out of this memory may execute slower because the processor cannot do as much work. The custom chips not only afford the amiga many capabilties in terms of graphics, and sound, but they also perform simple tasks like generating signals like RAS and CAS, and multiplexed addresses. These are required to use DRAMS which are currently the least expensive memory technology. In short, the custom chips provide what would otherwise be an expensive DRAM interface. Unfortunately, they only do this for CHIP memory. Both the 256K internal, and the 256K expansion memory on the A1000 are CHIP memory. Inside the A1000, none of the signals exsist to directly drive FAST memory. Therefore, to add FAST memory, the cost would be considerably higher. ( Read: considerably more complex ). Therefore, adding memory space to the A1000 by simply changing the DRAMs, and maybe running a couple of jumpers, is doomed to only being able to add CHIP memory space. The bad news is that the custom chips in the A1000 only have sufficient pins to address 512K. Therefore, if you already have 512K, its full. No more room. No Vacancy. You can of course add FAST memory to the A1000, but this requires a full and complete 68000<->DRAM interface including some sort of refresh, and other goodies. Because you have no sockets, you therefore need a new PCB. Further the A1000 expansion architecture requires a protocul called AUTOCONFIG which is the method by which the A1000 recognizes expansion boards, identifies them, and if they are memory, adds them to the system memory free list. This is not too awful difficult, but it is certainly not trivial, and therefore is beyond the reach of your average Amiga owner. If you are really interested in persueing this approach, and building your own board with lots of chips, I suggest you contact AMIGA developer's support. From there, you can obtain a copy ( at a nominal cost ) of the Amiga Schematics and Expansion Specifications manual. Please do not expect these people to "hold you hand" and walk you through every minute detail of the operation. They are extremely busy, supporting a large host of proffesional software developers. They are not really hardware hacks. You are warned that unless you are a good engineer, you may be in for a rough time. On the other hand, you could save an enourmous amount of time and energy by simply purchasing something that you know works from the many hardware companies supplying expansion memory for the A1000. This is not a sales pitch, it is simply good advice. Hedley Any effort to add memory space to CHIP memoryC This means, under certain conditions ( Hold and Moe
grr@cbmvax.UUCP (02/19/87)
In article <1430@cbmvax.cbmvax.cbm.UUCP> hedley@cbmvax.UUCP (Hedley Davis) writes: >Both the 256K internal, and the 256K expansion memory on the A1000 are >CHIP memory. Inside the A1000, none of the signals exsist to directly >drive FAST memory. Therefore, to add FAST memory, the cost would be >considerably higher. ( Read: considerably more complex ). > >You can of course add FAST memory to the A1000, but this requires a full >and complete 68000<->DRAM interface including some sort of refresh, and >other goodies. Because you have no sockets, you therefore need a new >PCB. Not to tread on Hedley's toes, but this does bring up an interesting point... You actually do have all the stuff in your Amiga needed to add 'FAST' ram! It's on that 'kickstart tower'. If someone wants to cover some new ground, I would suggest getting one of those ROM conversion kits, and then expanding the ram on the kickstart tower rather than the 'CHIP' ram. There are a number of advantages to this and the only disadvantage I see is that it won't auto-config. (no big deal). It wouldn't be that hard even to make a replacement board for 1-4MB. Power supply shouldn't be a problem if you remember that what you use inside, you can't extract from the external ports... Anyway, you could always expand both ways! If you're going to go out and void your warranty, you might as well have fun doing it... -- George Robbins - now working for, uucp: {ihnp4|seismo|rutgers}!cbmvax!grr but no way officially representing arpa: cbmvax!grr@seismo.css.GOV Commodore, Engineering Department fone: 215-431-9255 (only by moonlite)