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Adventures with Appleline
Posted by: thecloud on 2026-07-22 22:39:17 In the early 1990s, I was handed a slim beige box by a friend, who had gotten it from a person who worked at Apple, and asked if I needed a modem. She thought it was a modem, since it had a RS-232 port which said "modem" on the back panel, but it wasn't actually a modem. We didn't have a 24V AC power supply at the time, nor a serial cable of the appropriate gender, so I put it on a shelf to look at later. Like you, probably, I had no idea what an Appleline was. It has been described as "one of the rarest pieces of commercial hardware Apple has ever produced." Back in 1985, Apple wanted to sell its Macintosh Office solution to Business Customers. Macs could be networked with a propietary protocol suite called AppleTalk. However, many large enterprise customers had already invested in an IBM System 360-series mainframe and system network architecture, and were buying PCs to act as IBM 3270-compatible terminals. The Appleline Protocol Converter let you use a Mac as an IBM terminal, in an arguably less expensive way. It could translate between Apple's ASCII-based asynchronous serial communications and the IBM SNA world, which was EBCDIC-based and synchronous. This was no small feat. It needed a small dedicated computer to pull it off. But the Appleline had a secret: it wasn't actually made by Apple. It was a rebadged IRMALine, a product made by Digital Communications Associates (DCA), who had acquired it from Technical Analysis Corporation (TAC). Apple simply sprayed a coat of beige paint on the outside. This was confirmed a few years ago by Bill Landolina, one of the IRMALine engineers, as well as by me a few hours ago. I held onto the Appleline, with the idea that someday I would be able to hook it up and make it work. Very recently, I was motivated to take it down from the shelf, and to search out a working 24V AC power supply. These are generally unobtainium, but the Appleline box specified the exact model to look for: an Ault 326-4024. I was finally able to find one that was made for an IRMALine. There is a reference guide, designed for sales people demonstrating the Appleline, which explains how to set it up and what to expect. In particular, turning on the power is supposed to perform a self-test, causing the red, green, and yellow LEDs on the front panel to blink. I connected the power supply, flipped on the switch (because YOLO), and... nothing happened. First I verified with a multimeter that the power supply was actually putting out the expected AC voltage, and the problem was with the Appleline unit. So I removed the four screws on the bottom, opened it up, and had a first look at this board. It all looked very clean for 40 year old hardware. As expected, everything on the board says DCA, not Apple. There is a custom socketed Appleline ROM, and interestingly, there are 3 PROMs in sockets at one end which are dated 1987. I got as far as verifying the fuse had not blown and current was flowing to the far side of F1. But then I had a closer look at the capacitors. These aren't capacitors. Renco Electronics is known for making coils and transformers, so I assume these fall into that category. The smaller of the two black cylinders looks somewhat deformed and bulgy around the sides. Haven't seen anything that looks quite like these, but I'm not an EE. Do you recognize them? How to proceed? The inside of the case shows traces of what the plastic originally looked like (dark grey) before Apple applied the beige paint. Steve's design philosophy where even the inside of a case had to be beautiful clearly did not apply here. So the adventure remains on hold. Someday, this Appleline will awaken and my Mac 512K, running MacTerminal, will prompt me to Enter Password. I will respond with APPLES, the default password to the Appleline supervisor program, and then I will scream out, "I'M IN!!" But today is not yet that day.
Posted by: Nixontheknight on 2026-07-23 11:30:10 I'm intrigued to see how this goes
Posted by: thecloud on 2026-07-23 12:22:08 The closest thing I've seen to those is the flyback transformer on the analog board of a classic Macintosh, from the same era as the Appleline. But I'm scratching my head. Why would this need a high voltage transformer? It's not driving a CRT. Is it a voltage converter of some kind, e.g. AC to DC?
Posted by: gsteemso on 2026-07-23 16:16:15 AC to DC is, so far as I know, only and always done with diodes, albeit usually after AC to AC voltage adjustment via transformer. Transformers basically trade current for voltage, or vice versa. Inductors (coils) on the other hand are weird and counterintuitive, and I still haven’t quite wrapped my head around what you would use them for aside from noise filtering. (If anyone more knowledgable wants to chime in on that part, I’d be fascinated.) I also cannot fathom why this device would have two large-ish cores on the board, like that. The only suggestion I can come up with is that they might have something to do with the hardware connection to the IBM stuff, the design of which would have probably dated from at least twenty years prior. Does anybody know just what _exactly_ this thing was supposed to be hooked up to?
Posted by: NJRoadfan on 2026-07-23 17:14:20 Coax points to a SNA network run by a cluster controller. Basically this box replaces the classic 3278 (or similar) terminal with a Macintosh. IBM's terminals required a controller, unlike the relatively simple ASCII or DEC VT100 lines of the time. That controller could be thought of being similar to a modern router. It linked all the terminals and printers at a worksite back to the OS/390 mainframe located elsewhere. If you are looking for a modern replacement to use this box with, check this out: https://ajk.me/building-an-ibm-3270-terminal-controller
Posted by: thecloud on 2026-07-23 17:25:09 Does anybody know just what _exactly_ this thing was supposed to be hooked up to? The documentation I linked answers this question. The RS232 port labeled "modem" connects to your computer's serial port, where you would run terminal emulation software like LisaTerminal or MacTerminal to talk to it. The BNC connector labeled "controller" is connected via coax cable to an IBM Cluster Controller, either model 3274 (local controller) or 3276 (remote controller). The coax cable connection may be up to 5,000 feet long. Apple also offered its own "Apple Cluster Controller" which could be used instead of an IBM Cluster Controller... these are even more rare than the Appleline boxes.
Posted by: NJRoadfan on 2026-07-23 17:30:26 Realistically, I don't see many non-IBM cluster controllers being sold. They were pretty big with the whole vertical integration thing (lavish and expensive support contracts that promised high uptime). The last thing a site needed was downtime from some 3rd party piece of equipment glitching out. Remember, you local motor vehicles office was running these things!
Posted by: thecloud on 2026-07-23 17:36:10 If you are looking for a modern replacement to use this box with, check this out: https://ajk.me/building-an-ibm-3270-terminal-controller Thanks! I had found the Hercules emulator and its successor Hyperion, but they were handwavey about where to get the system software and I don't have enough experience with that world to really be motivated about setting it up, except perhaps as a demo.
Posted by: NJRoadfan on 2026-07-23 18:00:12 The licensing on early mainframe software is weird and early versions are freely available.
Posted by: gsteemso on 2026-07-23 18:19:54 I failed to state my question properly. What I was trying to ask was, is there any reason why hooking up to (for example) the 5000' of coax would require the device to have a chunky little transformer core on the board? Or is it probably for some other obscure purpose?
Posted by: NJRoadfan on 2026-07-23 19:24:43 I can't imagine the power supply being all that exotic. I'd expect the usual +5V along with -5V since RS-232 is involved. This entire device is so absurd that you can't hate it. Its got both a micro-controller and a 8085 CPU, all to connect to a then decade-plus old mainframe interface standard.
Posted by: chelseayr on 2026-07-24 05:01:54 inductors also can be used to smooth out 'dirty' ac>dc outputs, aside to (likely not in this particular peripheral but I'll still mention it nevertheless) also being used a a voltage booster whereas 5vdc input gets turned into 7vdc output
Posted by: adespoton on 2026-07-24 12:48:51 inductors also can be used to smooth out 'dirty' ac>dc outputs, aside to (likely not in this particular peripheral but I'll still mention it nevertheless) also being used a a voltage booster whereas 5vdc input gets turned into 7vdc output This was my thought too... it essentially airgaps the output, which might have been a requirement for putting this anywhere near an IBM vertically integrated stack. So those might not be in there for functional engineering reasons, but more as protection against voiding your IBM service contract.
Posted by: gsteemso on 2026-07-25 08:22:42 This was my thought too... it essentially airgaps the output, which might have been a requirement for putting this anywhere near an IBM vertically integrated stack. So those might not be in there for functional engineering reasons, but more as protection against voiding your IBM service contract. I think this seems the most likely suggestion to be accurate of any proposed thus far. For my opinion, arcane contract agreements seem like the most plausible reason for such a seemingly excessive design choice.
Posted by: thecloud on 2026-07-25 12:04:04 I think I might need to get @elemenoh to help look at this one. Meanwhile, I found the Mac software that DCA wrote to do file transfers over Appleline, also dated 1987. It came on a bootable 400K floppy disk with System 3.2 and Finder 5.3. Digital Communications Associates still have the copyright here. Oh, yes, also Apple Computer, but they don't make any claims on certain ideas and concepts. I wonder how temporary Apple's license actually was, and when it ran out. The program allowed full control over how ASCII was mapped to EBCDIC, as well as a number of selectable transfer types. COBOL must have been super useful. The button toggles between a large list of options. Selecting "Transfer Files..." from the File menu results in a friendly unfriendly dialog. Since the Appleline is not connected, it can't invoke the host application. Looking at the string resources with ResEdit, it appears that someone forgot to change "irma" to "apple".
Posted by: NJRoadfan on 2026-07-26 10:51:48 Heh, "abend" strings, how IBM-ese.
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