Replaces SWTPC 6800 Computer System
Peripheral Technology's first single board computer was 6809 based, but had we made a 6800 single board back in the 70's this is what it might have looked like. This board is modernized to use the iTX form factor and is powered by ATX power supplies. This provides many options for a case and power supply. The memory map of the PT68-1 is the same as an SWTPC 6800 computer. The same floppy and HD images that boot on an SWTPC 6800 will boot on the PT68-1 with no changes. One additional feature the PT68-1 has over the SWTPC is an additional IDE controller. With the MOVPAR program a user may backup IDE partitions to the second IDE port or copy them to another partition on either IDE port.
The PT68-1 uses the same SWTBUGA+ ROM that is used in the SWTPC MP-A2 processor board. No changes to the ROM are necessary. The disks and SD images that are used with the SWTPC system are used with the PT68-1 with no changes.
The PT68-1 uses an MC68B02 processor. The MC68B02 has the same instruction set as the MC6800. The main difference is the clock circuit. The MC6800 needs an MC6875 clock generator chip that is expensive and is becoming hard to find. The MC6802 uses a standard crystal or in the case of the PT68-1 an external oscillator.
The PT68-1 is an iTX sized board and will bolt in an iTX cabinet. It will also bolt into a normal ATX style case if you want a larger cabinet.
PT68-1 Specifications
Memory Map
| 0000-7FFF | RAM |
| 8000-8001 | ACIA (6850) - Slot 0 SWTPC 6800 |
| 8004-8005 | ACIA (6850) - Slot 1 SWTPC 6800 |
| 8008-800F | IDE Port 1 - Slot 2 - SS30-IDE SWTPC 6800 |
| 8010-8013 | RTC (146818) - Slot 4 SWTPC 6800 |
| 8014 | FDC Select - Slot 5 SWTPC 6800 |
| 8018-801B | FDC 2797 - Slot 6 SWTPC 6080 |
| 801C-801F | PIA (6821) - Slot 7 SWTPC 6800 |
| 8028-802F | IDE Port 2 |
| 8040-DFFF | RAM |
| E000-EFFF | EPROM |
| F000-FFF7 | RAM or EPROM depending on PAL used |
| FFF8-FFFF | 8 locations at top of EPROM mapped for reset/IRQ vectors |
The PT68-1 uses a PAL for address decoding. With a custom PAL the address map can be easily changed. An alternative PAL allows the address map to change so the Corsham SD shield can be used with the PT68-1 with no changes to the Corsham software.
Operation of FLEX 2 with a GoTek Floppy Emulator
It was necessary to modify the boot ROM to use a floppy emulator. FLEX 2 uses a non-standard sector format only on track 0. The sector numbering is:
0 2 3 4 5 6 7 8 9 10 Skipping sector 1 and having a sector 0
1 2 3 4 5 6 7 8 9 10 This is sector numbering for all other tracks.
The problem is the floppy emulator can't handle a missing sector 1 for track 0. This was overcome by adding another boot command to the Boot ROM. "D" is the usual command to boot from a physical floppy and "U" is the command to boot from a floppy emulator. The floppy emulator boots from sector 1 instead of sector 0.
Commands:
"D" - Boots from sector 0
"U" - Boots from sector 1
Other differences in FLEX2 are the addition of a "NEWDISKG" command that formats track 0 sequentially from sector 1 to 10.
There is also a "LINK1" command to allow linking FLEX for use with the floppy emulator. Link was renamed to LINK0 to help avoid confusion.
You have to "LINK" FLEX after copying it to a diskette or emulator before you can boot from it.
A FLEX2 boot disk with these additional commands can be downloaded; or if you order a GoTek or an IDE system from us, the additional utilities are included with your boot disk (USB thumb drive or SD memory card).
You may have a GoTek and a real floppy in a system at the same time. The only thing to remember is to use the appropriate "NEWDISK", "NEWDISKG", "LINK" or "LINK1" for the type of disk you are using.
Floppy Emulator
With good floppy drives hard to come by, to say nothing of blank diskettes, an alternative is needed. A GoTek drive with Flashfloppy Firmware update is capable of reading and writing disk formats as used by FLEX and OS9 . The GoTek uses USB memory sticks to store images of floppy disks and can hold thousands of disk images on a single USB stick. The images can be emailed as well as downloaded over the internet.
A GoTek allows users to download DSK image files from the FLEX users group, and there is a PC utility program to convert these image files to .IMA format used by the GoTek unit. Originally GoTeks had to have their firmware reflashed with Flashfloppy firmware, and it was necessary to add an OLED screen in order to tell which image you selected and to see error messages. It is no longer necessary to buy a GoTek and immediately modify it. Fortunately you can purchase ready to use GoTeks. GoTeks are now available with FlashFloppy firmware and OLED displays; in addition, they use a rotary knob to select images. This is a big improvement over the up and down push buttons that were on the original units.
This is a GoTek with Flashfloppy firmware and OLED. These units can be purchased on EBAY for under $50. Currently these units are not available on AMAZON. The units for sale on AMAZON do not have the OLED and Flashfloppy firmware.
You may use a real floppy drive with a GoTek should you have a need to read or write real diskettes.
If you boot on a GoTek with the FLEX2 image, you can create a boot disk on a real floppy drive. Simply use "NEWDISK", "COPY" and "LINK" to format the real floppy, copy files from the GoTek drive to the real drive, link FLEX and you have a bootable floppy disk.
Downloads
Hardware and Installation Manuals:
PT68-1 Manual User Manual, Schematics
Flex Installation Installation Guide - FLEX to SD
Source Code - SWTBUGA and HD Drivers
SWTBUGA-V1.3. ASM Source code for SWTBUGA V1.3 Boot ROM
WDISK - HD drivers to use with SWTBUGA.V1.2 pr V1.3
EPROMS - SWTBUGA /W HD Driver
SWTBUGA.PT68-1.V1.301.WDISK.BIN 8Ksize use a 2764
GoTek Utilities:
FloppyMaintenanceSetup.zip This Windows program can convert .dsk to .ima formats. Import and export files. Move files from one .ima image to another by use of import and export.
Click Here GoTek IMG.CFG File The configuration file you need for your GoTek to support FLEX/OS9 formats. Unzip and place on your USB memory stick.
GoTek Images
FLEX3.6800.Boot FLEX3 Boot Disk with HD drivers (Requires FD2/A), Utilities, ABASIC, BASIC, XBASIC, SPLM, 80 TRK DS/DD
6800.SDBASIC.Partition1.Release.ima Software Dynamics Basic Compiler
6800.ABASIC.Partition3.Release.ima Microware ABASIC Compiler + various source code
Software Manuals
Flex 2.0.pdf FLEX 2 User's Manual
FLEX 2.0 Advanced Programmers Manual.pdf You need this if you want to write programs.
TSC_6800_Editor.pdf Disk based EDIT manual not available - use "S" command to save to disk, EDIT <filename> to invoke
TSC6800 Assembler TSC 6800 Assembler Manual
XBASIC.PDF TSC XBASIC User Manual
BASIC.PDF TSC BASIC User Manual
A-BASIC V2.1F Compiler Reference Manual.pdf
A-BASIC FLEX Interpreter Reference Manual.pdf
| PT68-1-ASM | PT68-1 Assembled | $199 |
| PT68-1-SD/IDE | SD/IDE board, 40 conductor cable and SD card with FLEX3 loaded. Ready to boot | $29 |
| PT68-1-Bare | Bare PT68-1 Board | $25 |
| PT68-1-PAL | 22V10 and 16V8 Programmed for PT68-1 | $10 |