The Personal System/2 Model 30 and Personal System/2 Model 30 286 are IBM's entry-level desktop computers in their Personal System/2 (PS/2) family of personal computers. As opposed to higher-end entries in the PS/2 line which use Micro Channel bus architecture, the Model 30 features the Industry Standard Architecture (ISA) bus, allowing it to use expansion cards from its direct predecessors, the PC/XT and the PC/AT. The original PS/2 Model 30, released in April 1987, is built upon the Intel 8086 microprocessor clocked at 8 MHz and features the 8-bit ISA bus; the Model 30 286, released in September 1988, features the Intel 80286 clocked at 10 MHz and includes the 16-bit ISA bus.
IBM succeeded the Model 30 and Model 286 with the Personal System/2 Model 35 and Personal System/2 Model 40 subfamilies. Like their predecessors, the PS/2 Model 35 and PS/2 Model 40 use the ISA bus and were intended as entry-level models.
Development and release The PS/2 Model 30 was introduced on April 2, 1987, alongside the Model 50 and Model 60—entries in the PS/2 line which feature the new Micro Channel architecture bus, as opposed to the Model 30's Industry Standard Architecture bus previously used in IBM's PC/XT. The Model 30 is the most entry-level in the PS/2 lineup, with the dual-floppy-drive unit costing 1,695 and the floppy–hard drive combo unit costing 2,295—compared to $3,595 for the basic Model 50. With a variant of the Intel 8086 microprocessor clocked at 8 MHz, the Model 30 is rated roughly two-and-a-half times faster than its predecessors, according to IBM, while occupying a chassis roughly half the size. The Model 30 marks the first time IBM used this variant, known as the 8086-2, in a PC.
Manufacturing of the Model 30 was initially performed at IBM's facility in Boca Raton, Florida, by a core team of around 50 workers. IBM's engineers consolidated several off-the-shelf chips from their previous PCs into VLSI packages and designed the system board to take surface-mount devices—two strategies in wide use among expansion card manufacturers by the time of the Model 30's release. On launch day, 70,000 units of the entire PS/2 line—including the Model 30—were delivered to IBM dealers in the United States. In June 1987, manufacturing of the Model 30 was moved to Raleigh, North Carolina, with IBM offering all of the core team the option to transfer to the Raleigh facility. Computer industry analysts speculated that this relocation was to free up production lines of a newer, more advanced entry in the PS/2 family, at Boca Raton, where the Models 50, 60, and 80 were also being made. The Raleigh plant manufactured 2,000 Model 30s daily in June 1987, compared to 1,000 Model 50s and 800 Model 60s produced daily simultaneously in Boca Raton.
IBM introduced "financial workstation" versions of the Model 30 in November 1987. These Model 30s were intended for bank tellers and came packaged with a 50-key function keypad.
On September 13, 1988, IBM launched the PS/2 Model 30 286, which features the Intel 80286 microprocessor, clocked at 10 MHz. Per the updated microprocessor's 16-bit external data bus, the Model 30 286 also sports 16-bit AT bus expansion slots, allowing the computer to use expansion cards designed for the PC/AT; the original Model 30 has 8-bit ISA slots as used in the PC/XT. On announcement, the maximum amount of RAM was bumped from 640 KB to 16 MB—the maximum addressable amount for an 80286 processor. Additionally the integrated graphics chip and port were made VGA—a graphics chip standard which IBM introduced with the higher-end entries of the PS/2 line. The Model 30 286 marks IBM's return to the AT-compatible PC market, which IBM had invented with the release of the PC/AT in 1984. For seventeen months between the discontinuation of the PC/AT and the introduction of the Model 30 286, IBM offered no products with 16-bit ISA slots. Like the Model 30 before it, the Model 30 286 was also manufactured in Raleigh.
Specifications
Both the Model 30 and its 286 successor feature the same case design. Their "bleached-beige" chassis measures — roughly a third in volume of the PC/AT. The Model 30 weighs . The front and back of the case sport plastic bezels, the front featuring a sloping canopy design off-white in color, while the back is brown. The floppy drive resides in the middle of the front bezel, with the secondary drive bay—either housing a second floppy drive or a hard drive—to the right of the primary floppy drive bay. Should the computer be optioned with a hard drive, its bezel cover has a notch cut in it to show its status indicator. On the far right, next to the second drive bay, is a paddle switch, recessed beneath the front bezel's canopy design to prevent accidental actuation. This front-facing power switch itself is not directly attached to the power supply unit, but is instead linked via a metal rod to the "big red switch" of the power supply unit mounted in the back. A row of slots on the front bezel allow air to passively cool the components inside. A lock and key on the side of the chassis prevents the chassis from being opened up and disables the keyboard. While the higher-end PS/2s feature a modular construction with card-edge connectors for drives and a tool-less approach to user servicing, the Model 30 relies on ribbon cables for these connections and requires the removal of four screws to undo the case lid. The lid itself is made from steel, while the chassis holding the internal components in place is a stamped, U-shaped piece of metal with 0.75-inch folds.
Model 30 Two submodels of the Model 30 were available on launch: one with two 3.5-inch 720 KB floppy disk drives and the other with one 3.5-inch disk drive and a 20 MB hard disk drive. Three 8-bit ISA expansion slots are contained in a riser card positioned at the center of and running perpendicular to the system board, with the expansion cards running parallel, in order to save space internally and reduce the computer's physical footprint. The riser card inside the Model 30 was the first of its kind.
The original Model 30 features an Intel 8086 at 8 MHz, with no wait states. It provides 640 KB of random-access memory—128 KB worth of which in chips soldered to the system board, and the remaining 512 KB in the form of removable single in-line packages. The soldered RAM chips are rated for 125-nanosecond operations, while the two banks of SIP RAM have 9-bit chips. Several VLSI gate arrays on the system board consolidate the functions of parallel, serial, PS/2 mouse and keyboard, floppy and hard disk, and on-board graphics. The system board also eliminates jumpers for storing configuration settings; these settings are instead configured via software on a floppy disk provided by IBM and stored in battery-backed SRAM. Seek tests performed on the 3.5-inch floppy drive revealed that it performs at 300 milliseconds, 70 milliseconds slower than the 5.25-inch floppy drive featured in the PC/AT, while the 20 MB hard drive performs at 80 milliseconds—half the speed of the PC/AT's hard drive and marginally better than the PC/XT's.
IBM developed a bespoke display standard for the Model 30, dubbed Multi-Color Graphics Array (MCGA). This display incorporates elements of IBM's more-capable Video Graphics Array (VGA), as introduced in higher-end models of the PS/2 family, into the earlier Color Graphics Adapter standard introduced back in 1981. These include a 2-color 640-by-480-pixel graphics mode, a 256-color 320-by-200-pixel graphics mode (at a so-called "VCR-like resolution"), VGA's 15-pin D-sub connector and analog color signals, and a text mode with an 8-by-16-pixel character size (two pixels taller than EGA's text mode characters).
Model 30 286 Internally, the Model 30 286 features an Intel 80286 microprocessor clocked at 10 MHz. Instead of the pin-grid-array version of the 80286 as used in earlier IBM machines, the company opted for the plastic-leaded chip carrier version of the 80286, which was less expensive to produce and is less susceptible to damage when the user removes it from the chip's socket. The optional math co-processor slot meanwhile only supports dual-in-line-packaged 80287s. The packaging of removable RAM was upgraded from 125-ns SIPs to 120-ns SIMMs for the Model 30 286; only 256-kilobit or 1-megabit SIMMs are supported—the latter used in the stock 512 KB of RAM. It is necessary to install identical SIMMs in each of the four sockets available, meaning that RAM upgrades on the motherboard beyond 512 KB are limited to 1 MB, 2 MB, and 4 MB total. The computer supports up to 16 MB of RAM on a third-party external expansion card.
IBM used nine application-specific ICs on the system board both to reduce production cost and make the system board more compact. The more critical of these ASICs are the chipsets defining its AT compatibility, which were developed by VLSI Technology. These ASICs are packaged as surface-mount devices soldered to the board; virtually the only through-hole devices on the board comprise the keyboard controller and two BIOS ROMs, the 80286, and the optional 80287—only because they come in sockets.
The Model 30 286 abandons MCGA for full VGA compatibility. The VGA circuitry is backwards-compatible with EGA, CGA, and MDA (in capability and at the BIOS software level but not fully at the hardware level) and supports up to a resolution of 640 by 480 pixels at 16 colors, as well as 320 by 200 at 256 colors. As the VGA standard interface to the video monitor is fundamentally analog, not digital like the interface to CGA and MDA monitors, VGA (or MCGA) cannot be used with those older monitors. Thus, IBM recommended users purchase their IBM PS/2-styled VGA CRT monitors, available with either monochrome or color picture tubes—neither included in the base price of the Model 30 286. The Model 30 286's VGA circuitry can detect whether a monochrome or color IBM monitor is attached, providing an optimized palette of 64 shades of gray for the monochrome display. The Model 30 286's data path for its VGA circuitry is 8-bits wide, compared to most of the rest of the system's 16-bit wide data paths, and the teletype video routines, as located in its ROM, perform slower than on other members of the PS/2 range with 80386 processors owing to the 286's inability to copy ("shadow") ROM into RAM.
IBM manufactured the Model 30 286's optional 20 MB hard drive, while Alps manufactured its 1.44 MB floppy drives and Delta Electronics manufactured its non-autoranging, slimline 90.75 W power supply unit. The hard drive writes data using the MFM encoding standard; like the one in the original Model 30 before it, journalists remarked it as being slow. It paled in comparison to the AT's, according to PC Magazine, due to IBM limiting its data path to an 8-bit width and reducing the interleave skip factor from three to two. IBM included a disk-caching utility on the included Reference Disk in an attempt to help users offset its slowness.
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