rabbitholecomputing
Vendor The First
These "universal" serial-only CommSlot PCBs just showed up today, and so far, we've only confirmed that they physically fit in both CommSlot I and CommSlot II sockets, which is a relief. It has footprints for an ESP8266-based Adafruit ESP-12F ($6.95), Raspberry Pi Pico or Pico W stamp, (RP2040-based MCU), or the ubiquitous "Blue Pill" boards (Choose one). This Universal CommSlot serial boards are really simple. All it does is provide voltage translation (to 3.3V, from the 5V CommSlot interface) for the serial pins, a buffer, and a 3.3 volt regulator.
ONLY the serial signals are wired to the edge connector in this revision (2022a). J3 is an SPI pin header which brings out SPI signals from the three different modules to a 3.3V pin header. J4 is the same, but for I²C.
Here's the six-component Bill of Materials, which can cost as low as $5-6 per board. The cost of the ESP8266/Pi Pico/Blue Pill boards is in addition to the base BOM cost. The PCBs cost $2.45 each (shipped), because they're gold ENIG plated, and we didn't order very many. When these are fully tested, we'll eventually be releasing the board design files under an open source license, likely the CERN OHL-S V2 (strongly reciprocal), which is GPL-like, and will order a few hundred PCBs for resale. Until then, if you want one to tinker with, see below.
R1 and R2 are optional 4.7K ohm resistors (1%), to be used as I2C pull-ups, if you're making use of i2c. P/N is RC0603FR-074K7L.
Needless to say, this isn't fully-baked yet, but anybody who wants a PCB and the core BOM components, please let us know. Due to the cost of international shipping, it doesn't make sense to ship these abroad from the US. If anybody here would like to have a handful of blank PCBs sent to their non-American shipping address, please contact us via PM. We're willing to sell these PCBs at near-cost, as this is a hobby board at this point. The initial goal is to be able to use an ESP8266 to connect a Mac to "dial up" to modern Wi-Fi networks, using OpenTransport/PPP, and the ESP8266 or Raspberry Pi Pico W as a bridge to the outside world, albeit at serial speeds.
@David Cook, if you're interested in a PCB, we'll send you one for free. Due to the cost of international shipping, it doesn't make sense to ship these abroad. If anybody here would like to have a handful of blank PCBs sent to their non-American shipping address, please contact us via PM.
Since plenty of you might be wondering "why does this thing exist?", consider this...There are far more CommSlot-equipped Macs with obsolete, useless 28.8/33.6/56K modems still installed than there are CommSlot Ethernet boards in existence. Nobody has made a new CommSlot product in 25 years at this point, presumably. The TAM & Beige G3s were the last Macs that shipped with a CommSlot, in 1997. Plenty of people are making use of Ethernet CommSlot I & CommSlot II boards. If you have one and you're happy with it, this project probably won't be of much interest to you, at least in its current form.
As a reminder, there were a number of Mid-to-late-90s 68K and PPC Macs that were CommSlot equipped:
ONLY the serial signals are wired to the edge connector in this revision (2022a). J3 is an SPI pin header which brings out SPI signals from the three different modules to a 3.3V pin header. J4 is the same, but for I²C.
Here's the six-component Bill of Materials, which can cost as low as $5-6 per board. The cost of the ESP8266/Pi Pico/Blue Pill boards is in addition to the base BOM cost. The PCBs cost $2.45 each (shipped), because they're gold ENIG plated, and we didn't order very many. When these are fully tested, we'll eventually be releasing the board design files under an open source license, likely the CERN OHL-S V2 (strongly reciprocal), which is GPL-like, and will order a few hundred PCBs for resale. Until then, if you want one to tinker with, see below.
CL10B104KB8NNWC - 1x 100nF Capacitor, 0603 package, X5R or X7R, >= 10V |
CL21A106KPFNNNG - 2x 10uF Capacitor, 0805 package , X5R or X7R, >= 10V |
CL10B103KB8NNNC - 2x 10uF Capacitor, 0603 package, X5R or X7R, >= 10V |
74LVC3G34DC,125 - 1x ,non-inverting 3-element/triple buffer, VSSOP-8 package |
74LVC2T45DC-Q100H - 1x Dual 2-input NAND gate, VSSOP-8 package |
NCP1117LPST33T3G - 1x 3.3V Low-Dropout voltage regulator, SOT223-3 package |
Needless to say, this isn't fully-baked yet, but anybody who wants a PCB and the core BOM components, please let us know. Due to the cost of international shipping, it doesn't make sense to ship these abroad from the US. If anybody here would like to have a handful of blank PCBs sent to their non-American shipping address, please contact us via PM. We're willing to sell these PCBs at near-cost, as this is a hobby board at this point. The initial goal is to be able to use an ESP8266 to connect a Mac to "dial up" to modern Wi-Fi networks, using OpenTransport/PPP, and the ESP8266 or Raspberry Pi Pico W as a bridge to the outside world, albeit at serial speeds.
@David Cook, if you're interested in a PCB, we'll send you one for free. Due to the cost of international shipping, it doesn't make sense to ship these abroad. If anybody here would like to have a handful of blank PCBs sent to their non-American shipping address, please contact us via PM.
Since plenty of you might be wondering "why does this thing exist?", consider this...There are far more CommSlot-equipped Macs with obsolete, useless 28.8/33.6/56K modems still installed than there are CommSlot Ethernet boards in existence. Nobody has made a new CommSlot product in 25 years at this point, presumably. The TAM & Beige G3s were the last Macs that shipped with a CommSlot, in 1997. Plenty of people are making use of Ethernet CommSlot I & CommSlot II boards. If you have one and you're happy with it, this project probably won't be of much interest to you, at least in its current form.
As a reminder, there were a number of Mid-to-late-90s 68K and PPC Macs that were CommSlot equipped:
- Mac LC 575 (Performa 57x)
- Mac LC 580 (Performa 58x)
- Mac LC 630 (Performa 63x)
- Quadra 630
- Performa 5200 / 5260
- Performa 5300CD
- Power Mac 6200 (Performa 6200)
- Performa 6260 / 6290 / 6300 / 6310
- Power Mac 6300/120 (Performa 6320)
- Beige G3 (serial/modem-only, off the Personality Card)
- Twentieth Anniversary Mac