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Post by mrbombermillzy on Jan 1, 2020 10:06:11 GMT
What Ive always wanted to do is a '68 version of this, fitted with dual ported VRAM with some form of easy interface connector for future hacking purposes!
If I had the earlier VDC (or infact ANY working 128 machine! lol) I would buy this. Its very reasonably priced. Great work!
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Post by eslapion on Jan 3, 2020 19:04:15 GMT
What Ive always wanted to do is a '68 version of this, fitted with dual ported VRAM with some form of easy interface connector for future hacking purposes! If I had the earlier VDC (or infact ANY working 128 machine! lol) I would buy this. Its very reasonably priced. Great work! The '68 is used on the C128DCR which already has 64k of separate VDC RAM so I don't get the point. Also, dual port RAM could potentially be useful for greater speeds on the C64 and VIC-20 where RAM can be shared between the CPU and video chip but the VDC has RAM all to itself so what could possibly be the point of having dual port RAM with a VDC ?
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Post by mrbombermillzy on Jan 3, 2020 19:35:19 GMT
The '68 is used on the C128DCR which already has 64k of separate VDC RAM so I don't get the point. Also, dual port RAM could potentially be useful for greater speeds on the C64 and VIC-20 where RAM can be shared between the CPU and video chip but the VDC has RAM all to itself so what could possibly be the point of having dual port RAM with a VDC ?
There are many reasons for doing this. Its not about the amount of RAM.
If you recall, the VDC RAM is a bit of a 'walled garden'. i.e. you have to jump through hoops to change anything and even then, it wont be done in a hurry. (special techniques can be used to 'burst fill' the RAM quicker, but even still..)
Having an interface to the (faster) RAM would allow it to be accessed by another entity other than the VDC and at a higher speed.
Im thinking cartridge memory space, REC chip, etc.
Basically, the VDC RAM could be used as a double/triple screen buffer while the actual VDC just 'shifts' the data out. (The REC can even be used as a sort of blitter chip with some scope for better software sprites).
I know it would be some work to interface, but, hey, Im just saying thats what I would like! I think both a REU cart and a final chesscart could make for some interesting scenarios with this sort of hack.
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Post by eslapion on Jan 4, 2020 6:42:27 GMT
If you recall, the VDC RAM is a bit of a 'walled garden'. Having an interface to the (faster) RAM would allow it to be accessed by another entity other than the VDC and at a higher speed.
Im thinking cartridge memory space, REC chip, etc.
Basically, the VDC RAM could be used as a double/triple screen buffer while the actual VDC just 'shifts' the data out. (The REC can even be used as a sort of blitter chip with some scope for better software sprites).
I know it would be some work to interface, but, hey, Im just saying thats what I would like! I think both a REU cart and a final chesscart could make for some interesting scenarios with this sort of hack. Yeah, that makes sense but DPSRAM is still awfully expensive. The SRAM I put on SaRuMan-VDC exists in much faster variety, as fast as 12ns. It would be more technically complex but considerably less expensive to allow access to the same SRAM between the cycles used by the VDC and also during the HBI and VBI. The loss in speed wouldn't be much. I know Gideon Zweijtzer (64 Ultimate and 1541 Ultimate) created a VHDL version of the REC which uses SRAM.
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Post by mrbombermillzy on Jan 4, 2020 14:16:24 GMT
Yeah, that makes sense but DPSRAM is still awfully expensive. The SRAM I put on SaRuMan-VDC exists in much faster variety, as fast as 12ns. It would be more technically complex but considerably less expensive to allow access to the same SRAM between the cycles used by the VDC and also during the HBI and VBI. The loss in speed wouldn't be much. I know Gideon Zweijtzer (64 Ultimate and 1541 Ultimate) created a VHDL version of the REC which uses SRAM.
Thats another way of doing it.
Im more an assembly coder, so you may have to forgive me if I may not be able to brainstorm the design fully.
What you describe above sounds like perhaps DDR RAM, except you would be writing BOTH cycles when in HBL/VBL. Am I seeing it correctly?
Perhaps a circuit with Gideons REC chip implementation included with the fast RAM would be something like what I had in mind as an end goal.
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Post by eslapion on Nov 29, 2020 6:50:30 GMT
Saruman-VDC is still available directly from me or through Retroleum in the United Kingdom and Protovision or Polyplay in Germany.
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Post by eslapion on Apr 27, 2021 6:11:30 GMT
I have more than 100 units in stock!
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Post by eslapion on May 2, 2021 6:28:10 GMT
New lower price! 15$ each (13.50 Euros)
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Post by gsteemso on May 6, 2021 3:49:07 GMT
The version for the C64c is presently available at the same price. I must confess that I have thoroughly failed to grasp, well, SOMETHING about this. How does a RAM expansion for the 80-column chip in a C128 have any applicability to a C64c? I get the parallel use case involving the C16 / C116 / etc. Like the C128's VDC subsystem, that family of machines also has a 64K address space that's only populated by 16K. The C64c, not so much. Please un-bewilder-ate my poor brain!
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Post by eslapion on May 8, 2021 19:01:20 GMT
The version for the C64c is presently available at the same price. I must confess that I have thoroughly failed to grasp, well, SOMETHING about this. How does a RAM expansion for the 80-column chip in a C128 have any applicability to a C64c? I get the parallel use case involving the C16 / C116 / etc. Like the C128's VDC subsystem, that family of machines also has a 64K address space that's only populated by 16K. The C64c, not so much. Please un-bewilder-ate my poor brain! It's because you took this sentence totally out of its context. Let me explain. I also make another product called Saruman-TED and another one called Saruman-64. Saruman-TED will increase the RAM of a C16 from 16k to 64k. Saruman-64 replaces the DRAM ICs of a C64 or C64c completely but from an electronics point of view, they are extremely similar to Saruman-VDC. When you use Saruman-TED, you can completely remove the DRAM of a C16 if you want to. If you use Saruman-VDC, you can remove the 2 DRAM ICs reserved for the VDC if you want to. Saruman-64 takes the place of the DRAM (of a C64 or C64c) so you have to remove them. Yes, there is such a thing as an adapter to use Saruman-VDC to replace the RAM of a C64c but it's not very practical as Saruman-64 is less expensive. Also, there are people who have good experience with soldering who used a Saruman-64 to take the place of the VDC DRAM and got 64k for their VDC this way instead of using a Saruman-VDC - it's less expensive but it's more difficult.
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