processor. The model numbers included the letter 'U' (9836U, 9836CU, and 9920U). Later versions of the Series 200's included the 9816, 9817, and 9837. These systems were soon renamed as the HP Series 200 line, before being renamed again as part HP 9000 family, the HP 9000 Series 200. There was also a "portable" version of the Series 200 called the Integral. The official model was the HP9807. This machine was about the size of a portable sewing machine, contained a MC68000 processor, ROM based HP-UX, 3½ inch floppy disk drive, inkjet printer, a keyboard, mouse, and an electroluminescent display similar to the early GRiD Compass computers. It was not battery powered, and unlike the other Series 200's that were manufactured in Fort Collins, Colorado, it was made in Corvallis, Oregon. Series 300/400 The Series 300 workstations were based around Motorola 68000-series processors, ranging from the 68010 (Model 310, introduced 1985) to the Motorola 68040 (Model 38x, introduced 1991). The Series 400 (introduced 1990) were intended to supersede the Apollo/Domain workstations and were also based on the 68030/040. They were branded "HP Apollo" and added Apollo Domain/OS compatibility. The suffix 's' and 't' used on the Series 400 represented "Side" (as in Desk side) and "Top" (as in Desk top) model. The last two digits of the Series 400 originally was the clock frequency of the processor in MHz (e.g. 433 was 33 MHz). At introduction, the Series 400 had a socket for the MC68040, but since they were not available at the time, an emulator card with an MC68030 and additional circuitry was installed. Customers who purchased systems were given a guaranteed upgrade price of $5,000USD to the MC68040, when they became available. The Series 300 and 400 shared the same I/O interface as the Series 200. The 32-bit DIO-II bus is rated at 6 MB/s. Series 500 The Series 500s were based on the HP FOCUS microprocessor. They began as the HP 9020, HP 9030, and HP 9040, were renamed the HP Series 500 Model 20, 30, and 40 shortly after introduction, and later renamed again as the HP 9000 Model 520, 530 and 540. The 520 was a complete workstation with built-in keyboard, display, 5.25-inch floppy disk, and optional thermal printer and 5 MB hard disk. The 520 could run BASIC or HP-UX and there were three different models based on the displays attached (two color and