System 80 - Images (Outside and Inside)
The various System 80 models referred to in the text below are described in full on the System 80 Models page. Here you get close up and personal with a couple of them. The two units on display represent either end of the System 80 timeline. The first is an original MK I model. The second machine is a Blue Label model. These pictures reveal the innards of both, showing the major changes in hardware that occurred. The images can be matched up with the circuit diagrams and schematics from the Technical Manual reproduced on this page.
Clicking on the figures of naked or semi-naked System 80s and boards will give you a larger, more detailed view.
System 80 Mark I (version 1)
Figure 1a. The original Dick System 80 (MK I (version 1))
Figure 1b. System 80 (MK I, version 1) - The view with the cover off
Here you can see the self-contained power supply unit in the right hand corner, the cassette recorder and full-stroke keyboard sitting atop two circuit boards. Note the spaces for extra keys at the top of the keyboard mount. Some hobbyists took advantage of these and added keys in after-market modifications.The CPU board is on the left-hand side and the video interface card on the right hand side. These boards are connected to each other with two very stiff ribbon cables.
Figure 1b. System 80 (MK I, version 1) - fully naked
Here you can see both boards exposed. Note the eight 4116 RAM chips giving a total onboard memory of 16k. Also note the four ROM chips. This is not typical. Normally only three of these 4k ROM ICs would be fitted to MK 1 models. The forth IC is a 2k utility EPROM which, along with its socket, has been fitted by a previous owner.
Figure 1c. System 80 (MK I, version 1) - Video Interface Card
The VRAM consist of seven socketed 2102 chips. Models with this video interface card (the MKI v1 and MKI v2a) were only capable of uppercase, although third-party lower case mods were available. These consisted of another 2102 chip (to give full 8-bit wide video memory) and a replacement character generator.
Figure 1d. System 80 (MK I, version 1) - CPU Board
Note the large heat sink attached to the power transistor. With a large case and plenty of ventilation slots, the System 80 machines seldom had issues with overheating.
System 80 - Blue Label
Figure 2a. The Dick System 80 (Blue Label)
Refinements to the MKI saw two other "Black-Label" variants (versions 2a and 2b), which (among other things) introduced a volume control and level meter to the cassette deck and introduced more keys. Eventually all were superceded by the Blue Label model which had a full complement of keys in a similar arrangement to the original TRS-80 Model 1.
Figure 2a. The Dick System 80 (Blue Label) - Video Interface Card
Internally, the biggest change between the early MKI models (MKI version 1 and version 2a) and the later ones (MKI version 2b and Blue Label) was on the video interface card. In this board, the seven 2102 VRAM chips have been replaced by two 2114 ICs and there is a new character generator. With full 8-bit video memory, lower case is now standard. These newer boards are easy to recognise as the character generator has a vertical orientation from the circuit board's front edge rather than horizontal. The interface cards differ slightly between the MK1 version 2b and Blue Label in that the latter has some minor modifications to the cassette circuitry to accommodate feeding sound to a speaker.
Figure 2b. The Dick System 80 (Blue Label) - CPU Board
The CPU board remained much the same in all models, although later models such as the MK II and Blue Label had a 2k ROM EPROM and socket fitted as standard. The particular Blue Label unit shown here has had its factory-fitted 16k RAM expanded internally to 48k via the RAM piggyback method. This was a common after-market modification.
Figure 2b. The bottom of my Dick System 80 (Blue Label)
Designed for Australia it says but that's a Dick Smith marketing ploy of course. Also designed for Europe, and many other places. Note the copyright notice for the BASIC Interpreter from Microsoft, which shows that 12k of the ROM at least was entirely legal.