Due to a pending move, I won't be making another batch of these systems until the end of Summer at which time I'll also consider retiring it, although I will support systems that I've sold. The primary reasons are:

• The rising cost of quality components and supply chain issues
• A desire to spend more time on software development
• A customer who I feel ripped me off.

He complained the SD interface would not format new cards so after several message exchanges I sent a new and THOROUGHLY tested exchange system. Neither system was returned and his response was that both systems had the same issue so they were thrown in a box because he was "frustrated" even though he never provided a clear problem description. Dozens of other customers have had no reported issues and I've formatted nearly 100 SD cards with these systems. I highly suspect he simply doesn't understand CP/M disks, didn't read the documentation and/or was simply ham-fisted and broke both uSD sockets. I'd even offered a full refund if both systems were returned. This experience chewed up a lot of time and also what small profit I make from a batch of systems.

N.B. I consider one of the S/N 68/69 systems to be stolen merchandise.

This is a very small cased Z180 system that comes fully assembled and tested with CP/M 2.2. It can be used as-is or as a development / testing platform for software such as applications and/or operating systems (i.e. ZCPR, CP/M-3, MP/M, etc.). After initialization, this system runs with ZERO memory wait states since each wait state would result in approximately a 25% reduction in effective speed.

Case Size: 50mm x 50mm x 15mm or approximately 2" x 2" x 0.6"

Features:

• Zilog Z8S180 at 33.333MHz or 36.864MHz
• 512KB flash memory for boot code, CP/M 2.2 and a 496KB ROMdisk
• 512KB or 1MB of zero-wait SRAM for CP/M and a 436KB or 948KB RAMdisk
• 256 bytes of EEPROM
• 64 bytes of battery-backed SRAM
• Two USB serial ports with RTS/CTS handshaking (default of 115200 baud 8,N,1)
• MicroSD socket with a 25MHz SPI interface
• Real Time Clock (RTC) with rechargeable battery
• RUN (green) / HALT (red) bicolour LED
• A user-programmable LED
• An optionally enabled 2Hz LED indicating interrupts are working properly
• A RESET pushbutton
• USB powered

Included with purchase:

• An assembled and tested system as described above and like the one pictured
• A new 16GB or larger microSD card and adapter with an 8MB CP/M partition and a FAT32 partition with documentation including the BIOS & CP/M source code plus schematic and approximately 7.5GB of CP/M-era software including various application programs, CPMUG, Dr. Dobbs Journal, SIG/M, The Computer Journal, etc.

Required:

• A host computer with a USB port plus a terminal emulation program such as HyperTerm or TeraTerm
• A USB-A to mini-B cable or adapter
• Silicon Labs USB to UART VCP (Virtual COM Port) driver which is automatically installed by Windows or is downloadable from their website with versions for Linux, Android etc.

This system comes assembled and tested since all the components except the reset switch are SMD and construction is more difficult than through-hole projects. The 512KB system is field upgradeable to 1MB but requires the new RAM chip's legs to be bent and soldered piggy-back style to the existing SRAM. Due to availability of 33 MHz SMD processors, the installed one may not be a new device but no problems have been encountered with many dozens of them and MANY hours of testing. Likewise the CPLD. It should be noted that every system is tested for at least one full day before any sale.

A 36.864 MHz system is overclocked about 10.6% above the Zilog specifications and many of these systems have been run extensively at this speed with no anomalies being identified. This speed also allows the serial ports to be run at 230400 baud whereas the 33 MHz version is limited to 115200 baud for standard rates. The 33.333 MHz system is in full compliance with all component specifications.

The seller is the original designer / builder of this board and the author of the BIOS. The BIOS incorporates an AUTOEXEC option and it can also be re-assembled and tested as a .COM program without the need to alter or change the flash device.

Shipping and handling:

• Shipping is via Canada Post and includes tracked airmail within Canada and USA or NON-TRACKED airmail for other countries. Tracking outside Canada and USA is an optional extra and if the purchaser doesn't choose it, they accept the liability for any lost packages. Not all countries support small packet tracking so if in doubt, please send an inquiry message to the seller. Any taxes and/or duties are the responsibility of the purchaser.

Disclaimer:

• These systems and their software are for hobbyist use only. They have been assembled on a reasonable efforts basis and are tested as working before shipment.