Timex 2068 : 128kB ROM + 512kB RAM
Internal memory upgrade for Timex Sinclair 2068, Timex Computer 2068 and Unipolbrit Komputer 2086. 128kB ROM, extra 512kB RAM.
ZXVGS UPB upgrade
Was designed in 2001 year. Allowed two operation modes: 2068 and ZXVGS, selected by manual switch. 32kB SRAM was seen only in EXROM bank: in 2068 mode in top half, in ZXVGS mode in bottom. For the EPROM there were seveal options depending on its size - 32kB, 64kB, 128kB.
Was made as ZXVGS mode only, using 64kB ROM (two ZX128 banks, ZXVGS code in ROM0, second half used for TR-DOS traps) and 32kB SRAM.
128kB PEROM and 512kB SRAM
In year 2005 the prices of PEROM (Flash EPROM) and SRAM got lower, so most advanced upgrade can be made.
The best solution for the PEROM switching is probably the FlashD0 board, upgraded in v004 version with EXROM option and write protection.
Switching of the SRAM should keep compatibility with ZXVGS UPB and extension called Larken ramdisk.
- Each chunk can point to Home or Dock/EXROM.
- Dock and EXROM are exclusive. Only one of them can be
selected at a time.
- Screen is located in Home, chunks 2 and 3.
The 512kB SRAM is seen as 8 pages of 64kB. Two ports can be used: 7 (#07) port or 15 (#0F).
Initial value (after reset) is #00, so page 0 is selected, seen in upper half of Dock and as write protected.
- Bits 0..2 - select page 0..7.
- Bits 3 and 4 are ignored. Should be 0.
- Bit 5 controls page size. When is 0, the selected page is seen only in upper half of address space - 32768..65535 (#8000..#FFFF). This way only 256kB are accessible, while second 256kB is hidden. When is 1 (add 32 to page number), the page is seen in whole address space - 0..65535 (#0000..#FFFF).
- Bit 6 controls write-protection. To remove write-protection, add 64 to page number - values 64..51 (#40..#47).
- Bit 7 selects where the SRAM is seen. When is 0, selected page is in Dock and both ports 7 and 15 can be used. When is 1 (add 128 to page number), the page is in EXROM and the port at address 7 is disabled (only port 15 can be used for next changes).
|7 (15)||0..7||32kB in upper
Dock, write protected|
|7 (15)||32..39||64kB in Dock, write protected|
|7 (15)||64..71||32kB in upper
|7 (15)||96..103||64kB in Dock, writeable|
|15||128..135||32kB in upper
EXROM, write protected|
|15||160..167||64kB in EXROM, write protected|
|15||192..199||32kB in upper
|15||224..231||64kB in EXROM, writeable|
Files for download
- 68lr-003.zip 48.2kB (2006-06-04 19:44)
- Upgrade board v003 for 512kB SRAM, not tested.
- upb-inst.txt 9.5kB (2001-08-26 16:28)
- [en] Description of ZXVGS UPB upgrade and its emulation.
Links to other pages
- [en] Memory upgrade description.
- Timex Sinclair 2068
- Timex Sinclair 2068. Produced in 1983/84 for USA and Canada markets.
- Timex Computer 2068
- Timex Computer 2068.
- Unipolbrit Komputer 2086
- Unipolbrit Komputer 2086. Polish version of Timex Computer 2068.
- 128KB - 512KB PEROM - FlashD0
- 128KB or 512KB PEROM (or Flash EPROM) for Spectrum compatibile computers. Can support 4MB RAM upgrade and be base for ZXVGS installation.
- Larken Interfaces
- Floppy controller and ramdisk.
- ZXVGS UPB
- ZXVGS for upgraded Unipolbrit Komputer 2086 or Timex Computer 2068.
- CPM22QED UPB
- CP/M 2.2 compatibile system for Timex 2068 computers with extra RAM and disk interface. Supports YAMOD.IDE8255 and YAMOD.ATBUS.
- Dock bank : Timex
- The 64kB memory bank known from Timex computers. Timex memory map.