From: Mark Tearle Date: Fri, 14 Sep 2001 12:29:27 +0000 (+0000) Subject: Added memory map for vending machine X-Git-Tag: ROMW~167 X-Git-Url: https://git.ucc.asn.au/?p=uccvend-snackrom.git;a=commitdiff_plain;h=8f46804f03981b73034ee21e5b7f9104100c0dc2 Added memory map for vending machine --- diff --git a/doc/memorymap b/doc/memorymap new file mode 100644 index 0000000..e445a4d --- /dev/null +++ b/doc/memorymap @@ -0,0 +1,64 @@ +From fryers@ucc.gu.uwa.edu.au Fri Sep 14 20:28:08 2001 +Date: Sat, 8 Sep 2001 12:22:39 +0800 +From: Simon Fryer +To: Mark Tearle +Subject: [Vending Machine Memory Map] + +----- Forwarded message from Simon Fryer ----- + +Evening + +Had a look at the circuit diagram for the vending machine this evening. Tried +to work out how all the I/O is arranged in memory as viewed by the HC11. For +the most part, only the address lines A11, A12 and A13 are decoded into +useful addresses. This means that to drive all the devices except for the +EPROM and the FLASH memory, A0 to A10 can be ignored and any value can be used. +The two memory chips actually care about the state of A0 to A10. I suspect that +the devices built onto the HC11 sit in memory somewhere but I am not sure +where yet. + +As far as I can tell, the memory map is as follows: +0x8000 to 0xFFFF - EPROM. 27C256 +0x3800 to 0x3FFF - U14. 74HC374 - 8 * D type flip flops. Here the data bits + are latched and taken off to various devices. (read serial I/O by + toggling data lines). + D0, D1 - Bill Valadator + D2, D3 - Display - D2 is data, D3 is clock (I think) + D4, D5, D6 - Snack Motors. D4 is data for the row decoder. D5, D6 + form part of the column decoders as far as I can tell. +0x3000 to 0x37FF - U13. 74HC374. For the changer - dispenses change and/or + counts change I think. Just latches data to the device. +0x0800 to 0x0FFF - U12. 40Z12. The Flash memory. +0x1800 to 0x1FFF - U7. 74HC245. This IC is a tristate buffer. It is used + for reading in the status of serveral switches. These switches are + the cost, door and soldout switches. +0x2000 to 0c27FF - U5. 74HC245. This reads in the status of the switch + block 1. These switces are LANG, LANG, FORCE, PROMO, MULTI and WN-SNK. + suspect these are read on startup to provide running state. +0x2800 to 2FFF - U6, 74HC245. This reads row 1-5,6-9 onto the data bus. + +There are some other bits of the circuit diagram that I want to get my head +around but I am going to leave that for another night. + +Some more good news. I has having a look through one of the junk rooms at +home and found that I have a nice collection of 27C256 EPROMS sitting on some +old ISA boards. They have a difficult to remove plastic sticker over the UV +window. These stickers are not Leatherman proof though. + +Next couple of steps... read up on the internals of the HC11. We have the +simple model with only minimal useful stuff on board. + +Also, to get a HC11 assembler and a working EPROM writer. + +See Ya +Simon + +-- +------------------------------------------------------------------------ +"Well, an engineer is not concerned with the truth; that is left to +philosophers and theologians: the prime concern of an engineer is +the utility of the final product." +Lectures on the Electrical Properties of Materials, L.Solymar, D.Walsh + + +----- End forwarded message -----