Editing IBM 3270 PC/GX

{{Infobox computer
| name          = IBM 3270 PC/GX
| image         = [[File:IBM AT GX Computer.jpg|260px]]
| caption       = IBM 3270 PC/GX — XT-derived extended-graphics workstation (system unit 5371) with 1024 × 1024 APA and IBM 5379 19" display
| developer     = IBM Entry Systems Division, Boca Raton, in cooperation with IBM 3270 / GDDM groups
| manufacturer  = IBM
| type          = High-resolution mainframe graphics workstation
| release date  = July 1984 (announced alongside the 3270 PC/G)
| discontinued  = 1987 (alongside the rest of the 3270 PC line)
| cpu           = Intel 8088 @ 4.77 MHz — same chassis as [[IBM 3270 PC]]
| memory        = 384 / 512 / 576 KB depending on submodel (12 / 14 / 16)
| storage       = 5.25" 360 KB DSDD floppy (1 or 2) + optional hard disk
| display       = '''IBM 5378 Display Attachment Unit''' (external converter box, larger than the /G's 5278) driving '''IBM 5379 Color Display''' (19", available as 5379-C01 colour or 5379-M01 monochrome). Resolution: '''1024 × 1024 APA'''
| sound         = PC speaker
| os            = '''3270 PC Graphics Control Program (GCP)''' + PC DOS — same as the [[IBM 3270 PC/G]] but driving the larger display and higher resolution
| predecessor   = [[IBM 3270 PC]] (5271 — text-only) and [[IBM 3270 PC/G]] (smaller-display sibling)
| successor   = IBM 3270 Workstation Program (1987) on standard PCs with appropriate graphics; IBM 6090 Graphics System for CAD/CAM
| model         = '''5371''' — '''same system unit as the [[IBM 3270 PC/G]]''' (not 5372). The /GX is differentiated from the /G by its 5378 attachment unit and 5379 19" display
}}

The '''IBM 3270 PC/GX''' is the extended-graphics ("GX") variant of the [[IBM 3270 PC]] family, announced by IBM in '''July 1984''' alongside the standard graphics [[IBM 3270 PC/G|PC/G]]. The "GX" suffix designates '''Graphics eXtended''' — the /GX provides '''1024 × 1024 APA resolution''' (significantly higher than the /G's 720 × 512) via a larger external Display Attachment Unit driving a 19" IBM 5379 monitor.<ref>IBM GA33-3141-0, ''Introducing the IBM 3270 Personal Computer/G and /GX Workstations'', May 1984.</ref><ref>https://en.wikipedia.org/wiki/IBM_3270_PC</ref>

== Important Machine-Type Note ==

The 3270 PC/GX uses '''system unit 5371''' — '''the same machine type as the [[IBM 3270 PC/G]]'''. There is '''no separate "5372"''' for the GX in any IBM source the wiki has located. The /G and /GX are differentiated by their attached display hardware:

* '''[[IBM 3270 PC/G]]''': IBM 5278 Display Attachment Unit + IBM 5279 14" Color Display, 720 × 512 APA.
* '''3270 PC/GX''' (this page): IBM '''5378''' Display Attachment Unit + IBM '''5379''' 19" Color Display, '''1024 × 1024''' APA.

The AT-based equivalent (PC AT/G and AT/GX) uses '''system unit 5373''', not 5371.

== Launch and Pricing ==

* Announced July 1984 alongside the /G.
* Reference document: IBM '''GA33-3141-0''' ''Introducing the IBM 3270 Personal Computer/G and /GX Workstations'' (May 1984).
* Launch price: '''$18,490''' (system + display), '''~$20,000''' for a working configuration with software and cables.<ref>https://en.wikipedia.org/wiki/IBM_3270_PC</ref> The /GX is roughly '''65% more expensive''' than the /G — the premium pays for the 1024 × 1024 vector graphics capability and the 19" monitor.
* '''Discontinued 1987''' alongside the rest of the 3270 PC line.

== Models ==

Same model numbering as the [[IBM 3270 PC/G]]:

{| class="wikitable styled-table" style="width:70%; text-align:center;"
|+'''IBM 3270 PC/GX (5371) submodels'''
! Submodel !! Storage !! RAM
|-
| 12 || 1 × floppy || 384 KB
|-
| 14 || 2 × floppy || 512 KB
|-
| 16 || floppy + HDD || 576 KB
|}

== Hardware ==

The 5371 system unit is identical between PC/G and PC/GX. The PC/GX-specific hardware is all in the external display subsystem:

* '''IBM 5378 Display Attachment Unit''' — larger and more capable than the /G's 5278. Drives the 5379 19" monitor at 1024 × 1024 with full-screen vector graphics.
* '''IBM 5379 Color Display''' — 19" colour CRT. Two variants:
:: '''5379-C01''' — colour.
:: '''5379-M01''' — monochrome.
* '''IBM 5277 mouse''' — same 3-button mouse as the /G.
* All system-unit cards (Keyboard Adapter, 3270 PC Display Adapter, APA, PSS, 3278/79 Emulation Adapter) are the same as the standard [[IBM 3270 PC]].

== Resolution and Graphics ==

* '''1024 × 1024 APA''' (Extended All Points Addressable) — the defining 3270 PC/GX capability.
* CGA-compatible 320 × 200 / 640 × 200 modes for DOS software (downscaled / windowed to the 19" 5379).
* Sufficient resolution for sustained CAD-style line drawings, mainframe-generated GDDM plots at multi-megapixel detail, and engineering documentation reading.

== Operating Environment ==

Same as the [[IBM 3270 PC/G]] — Graphics Control Program (GCP) with multi-session windowing, GDDM release 4+ support on the mainframe, local pan / zoom that does not require host round-trip, mouse input via IBM 5277.

The /GX's higher resolution means each mainframe session window can be larger than on the /G's 5279, and more of them can be visible simultaneously without overlap.

== Common Faults ==

The /GX inherits all of the chassis-level faults of the [[IBM 3270 PC]] (RIFA mains-suppression caps; tantalum bypass shorts; ageing 130 W IBM XT PSU). /GX-specific faults are dominated by the rarity of the 5378 / 5379 pair:

* '''IBM 5378 Display Attachment Unit''' — '''the rarest single component in the PC/GX system.''' Built specifically for high-resolution vector graphics; not interchangeable with the /G's 5278.
* '''IBM 5379 19" CRT''' — '''premium 19" tubes are scarce''' and command high prices when available. A failed 5379 effectively retires the PC/GX from operation unless a donor 5379 can be sourced.
* '''75-pin cable''' between 5378 and 5379 — proprietary IBM; verify pinout against GA33-3141-0 if you must replace it.
* '''GCP system diskettes''' — image immediately if you have an original set.

== Service Documents ==

* '''IBM GA33-3141-0''' — ''Introducing the IBM 3270 Personal Computer/G and /GX Workstations'' (May 1984). Primary reference.
* '''IBM SA38-0037-00''' — ''Personal Computer Family Service Information Manual'' (July 1989), Chapter 10. Covers /GX as well as the standard 3270 PC and /G.

== Related Pages ==

* [[IBM 3270 PC/GX Maintenance Guide]]
* [[IBM 3270 PC/GX Troubleshooting Guide]]
* [[IBM 3270 PC/GX Capacitor Replacement Guide]]
* [[IBM 3270 PC]] — base text-only 3270 PC family member
* [[IBM 3270 PC/G]] — smaller-display graphics sibling (same system unit type 5371)
* [[IBM PC XT (5160)]] — chassis ancestor

== References ==

* [https://www.bitsavers.org/pdf/ibm/pc/3270/3270_PC/GA33-3141-0_Introducing_the_IBM_3270_Personal_Computer_G_and_GX_Workstations_198405.pdf IBM GA33-3141-0 (May 1984)]. Primary PC/G and /GX reference.
* [https://en.wikipedia.org/wiki/IBM_3270_PC IBM 3270 PC — Wikipedia].
* [https://www.ibm.com/docs/en/gddm?topic=gddm-3270-pcg-3270-pcgx-workstations IBM GDDM Documentation — 3270 PC/G and 3270 PC/GX Workstations].
* [http://bitsavers.org/pdf/ibm/pc/SA38-0037-00_Personal_Computer_Family_Service_Information_Manual_Jul89.pdf IBM SA38-0037-00 (July 1989)], Chapter 10.

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