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Sure. And sometimes having a graphics dispaly was more important that clearer text. However, you can have both the MDA and CGA cards in the same machine, even in a 5150. If you're going to take up a slot to provide a printerport, you might as well put an MDA card there, which will give you said printer prot and a mono display output. You can have the CGA as well, and use that as the default display if you want to. I thought it was the 'Game Control Adapter' or soemthing like that. IIRC, it was just a set of 555-like monostables (actually a 558, which is effectively a chip containing 4 555 times wired as monostables). The joystick pot is the timing resisotr (there is probably a series resisotor on the card) and there's an timing capacitor.Bascially, software triggers it, starts counitng up, and stops when the monostable times out. I am not sure what resolution you could get if you wrote your own software (ie. how high a count you could get with the standard components), but possibly if you tweaked the R's and C's on the board you might get enough resolution to read out an LDRR for this Not just a plug change[1]. The CoCo joystick inputs are genunie voltage inputs, the joystick pot uses all 3 terminals. Track wired across the 5V supply, slider to the input. The IBM (and Apple ][) joysticks are varable resisotrs, betwee nthe +5V line and the input. It is, of course, tricial to rewire the Radio Shack joystick when you realise this. [1] as an aside, one of my favourit cartons shows a chap handing over a car radio for reapir. The caption is 'I think it needs a plug change and the valves ground in' Somewhere I have a fairly high end joystick for the Apple ][ which uses all 3 termianls of the pots and uses said pots to control currnet sources that are fed into the Apple inputs. Give the operation of the 558 (discharge the capacitor, wait for it to reach a certain voltage), I think this would work very well. It would obviosuly also work with the IBM Game Cotnrol Adapter AFAIK all could. Certainly the oldest schematic I've seen in the TechRef shows the necessary parts fo the modification (the socket for the 74S158, etc). Later on, IBM actually seem to ahve sold a 256K-640K Planar for the 5160 (which is, of course, the smae board, wit hthe 74S158 soldered in, pads E1 and E2 jumpered, anf the approrpatie RAMs fitted). Ar at least my Techref has an entire set of schemaitcs for it (which are almost identical to the previous pages coverign the 64K-256K planar). Nwo, IIRC, pads E3 and E4 o nthe 5160 planar were also a jumper on an input of the RAM mampping PROM. So there are actally 4 pssible memory cofigurations -- the 2 we all know about (4 rows of 64K chisp, 2 rows of 256K, 2 rows of 64K) and 2 othes. I think one of those was to have 4 rows of 16K chips (4816s) for a 16K-64K XT Planar. I can't remmber wha the last one was. Something like 32K rows??? -tony