TE-1508 : Internal 512KB RAMDisk !

2 Replies

Ok, my tests are OK on the prototype board.

TE-1508_RAMDisk

Here are the module features :
– Reference TE-1508
– 512KB of static RAM
– 16 pages of 32KB located in the ME1 zone
– Software selection of the page
– Software Activation/Desactivation (for example the IWS video interface uses same zone in ME1)
– Optional CR-2032 backup battery
– Optional write protection by jumper.

The page selection uses a very special feature of the LH5801 processor which was never being used before… because Sharp never routed this pin !
The data bus can work as a multiplexed bus like the Intel 8052 from the MCS51 family. It means that at one time data are on the bus and another time it’s something else. And this is f… good feature ! I don’t have to use many logical cells. Page 42 of the Technical Reference Manual describe it as the ATP instruction. It pushes the accumulator value on the data bus and provides all signals to store it in a latch. And here we just have to plug an octal latch.

Manual routing is done !
Installing it in your Sharp PC-1500(A) will need some wrapping wires…
TE-1508_Reduce

I need some tests with the final board and i will tell you the price…

Is it enough to store your programs ? 😀

2 thoughts on “TE-1508 : Internal 512KB RAMDisk !”

  1. Paul Chambre

    Is that extra signal from the CPU the white wire running around the back? Or did you find an extra pin on the expansion port to carry it?

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    1. Rom1500 Post author

      Hi Paul.
      That’s right, it’s the white wire coming from inside the PC-1500 !
      There are 4 unused pins on the connector.
      I have to check if they are really unconnected and if it’s the same with the peripherals : CE-150, CE-153, CE-158 and CE-162E.
      If yes i will have place for :
      – P0
      – ME0 (faster than the DME0)
      – BRQ (Bus request)
      – BAK (Bus acknowledge)
      The last two are for multi-CPU or DMA controller.

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